Driveshaft-damper tuning

ABSTRACT

Attenuation strips are provided for use in driveshaft dampers, and driveshaft dampers are provided for use in driveshafts to dampen or attenuate aspects of noise, vibration, and harshness (NVH). Systems and methods for making and using driveshaft dampers are further provided. The driveshaft dampers may be made using a helical-winding process and include attenuation strips with elongate protrusions. Various embodiments of helically-wound driveshaft dampers include a core and one or more attenuation strips helically wound around the core. The driveshaft dampers may be tuned to provide improved NVH reduction by reducing problematic NVH for a particular driveshaft as installed in a particular vehicle.

CROSS-REFERENCE TO PRIORITY APPLICATIONS

This application is a continuation-in-part of U.S. patent applicationSer. No. 17/076,079 for a Driveshaft Damper, (filed Oct. 21, 2020),which is a continuation of U.S. patent application Ser. No. 16/198,089for Methods for Making Driveshaft Dampers, (filed Nov. 21, 2018), nowU.S. Pat. No. 10,844,928, which itself claims the benefit of U.S. PatentApplication No. 62/589,806 for Driveshaft Dampers and Systems andMethods for Making the Same (filed Nov. 22, 2017) and U.S. PatentApplication No. 62/748,024 for Driveshaft Dampers and Systems andMethods for Making and Using the Same (filed Oct. 19, 2018). Thisapplication also claims the benefit of U.S. Patent Application No.63/117,162 for Driveshaft-Damper Tuning (filed Nov. 23, 2020). Each ofthe foregoing commonly assigned patent applications and patent is herebyincorporated by reference in its entirety.

FIELD OF THE INVENTION

The present disclosure relates to driveshaft dampers that may beinstalled in driveshafts to dampen or attenuate noise, vibration, andharshness (NVH), and systems and methods for making and using driveshaftdampers. The present disclosure further relates to the use of driveshaftdampers in various power-transfer systems, including automotivedrivetrains, propeller shafts, industrial machinery, and otherequipment.

BACKGROUND

Many kinds of machinery use a driveshaft for power transfer. Driveshaftsare commonly used in automotive powertrains, such as in cars, trucks,tractors, all-terrain vehicles, rolling stock, and heavy machinery.Additionally, driveshafts are commonly used in marine powertrains, suchas in boats and other marine vessels and aquatic machinery. Further,industrial machinery in a manufacturing facility or a processing plantmay use driveshafts for power transfer. Those having ordinary skill inthe art will appreciate numerous other applications that utilizedriveshafts.

A driveshaft conventionally employs a driveshaft damper to helpattenuate aspects of noise, vibration, and harshness arising fromvarious sources. Noise, vibration, and harshness are commonly referredto collectively as “NVH” throughout the automotive and various otherindustries. NVH can sometimes be transmitted or amplified to othercomponents and/or into the passenger cabin of a vehicle. It is desirableto dampen or attenuate NVH associated with a driveshaft and relatedmachinery to provide for quieter and smoother operation, to reduce wearand tear, and to improve operator comfort. Sometimes, a driveshaft maytransmit or even amplify NVH originating from various powertraincomponents or from outside sources. For example, an automotivedriveshaft may transmit NVH into the cabin of a vehicle, causing cabinoccupants to experience annoying or uncomfortable aspects of NVH, suchas road noise. A need therefore exists to provide improved driveshaftdampers to better dampen or attenuate NVH, providing for (i) quieter andsmoother powertrain operation, (ii) reduced wear and tear on powertrainand other components that may be vulnerable to various aspects of NVH,and (iii) improved operator comfort such as by reducing cabin noise.

Some driveshaft dampers are known in the art. For example, the followingcommonly assigned patents, patent applications, and patent applicationpublications provide driveshaft dampers that address NVH and otherissues, each of which is hereby incorporated by reference in itsentirety:

-   U.S. patent application Ser. No. 14/317,636, filed Jun. 27, 2014,    now U.S. Pat. No. 9,599,147, which issued on Mar. 21, 2017, which is    a division of U.S. patent application Ser. No. 13/681,851, filed    Nov. 20, 2012, now U.S. Pat. No. 8,801,526, which issued on Aug. 12,    2014, which is a continuation-in-part of U.S. patent application    Ser. No. 12/650,763, filed Dec. 31, 2009, which itself claims the    benefit to U.S. Patent Application No. 61/141,952, filed Dec. 31,    2008, and U.S. Patent Application No. 61/143,610, filed Jan. 9,    2009;-   U.S. patent application Ser. No. 14/585,859, filed Dec. 30, 2014,    now U.S. Pat. No. 10,641,354, which issued May 5, 2020, which claims    the benefit of U.S. Patent Application No. 61/922,562, filed Dec.    31, 2013, and which is a continuation-in-part of U.S. patent    application Ser. No. 14/317,636, filed Jun. 27, 2014, now U.S. Pat.    No. 9,599,147, which issued on Mar. 21, 2017, which is a division of    U.S. patent application Ser. No. 13/681,851, filed Nov. 20, 2012,    now U.S. Pat. No. 8,801,526, which issued on Aug. 12, 2014, which is    a continuation-in-part of U.S. patent application Ser. No.    12/650,763, filed Dec. 31, 2009, which itself claims the benefit to    U.S. Patent Application No. 61/141,952, filed Dec. 31, 2008, and    U.S. Patent Application No. 61/143,610, filed Jan. 9, 2009;-   U.S. patent application Ser. No. 12/256,553, filed Oct. 23, 2008,    and published as U.S. Pub. No. 2009/0048031 on Feb. 19, 2009, which    is a continuation of International Application No. PCT/US07/72529,    filed Jun. 29, 2007, and published as International Pub. No. WO    2008/005863 A2, which itself claims the benefit of U.S. Patent    Application No. 60/806,379, filed Jun. 30, 2006;-   U.S. patent application Ser. No. 11/422,631, filed Jun. 7, 2006, and    published as U.S. Pub. No. 2006/0276250 on Dec. 7, 2006, which    claims the benefit of U.S. Patent Application No. 60/688,054, filed    Jun. 7, 2005;-   U.S. patent application Ser. No. 11/422,660, filed Jun. 7, 2006, and    published as U.S. Pub. No. 2006/0276251 on Dec. 7, 2006, which    claims the benefit of U.S. Patent Application No. 60/688,054, filed    Jun. 7, 2005;-   U.S. patent application Ser. No. 11/422,759, filed Jun. 7, 2006, and    published as U.S. Pub. No. 2006/0276252 on Dec. 7, 2006, which    claims the benefit of U.S. Patent Application No. 60/688,054, filed    Jun. 7, 2005;-   U.S. Pat. No. 6,370,756, which issued on Apr. 16, 2002, from U.S.    patent application Ser. No. 09/572,767, filed May 17, 2000;-   U.S. Pat. No. 5,976,021, which issued on Nov. 2, 1999, from U.S.    patent application Ser. No. 08/892,146, filed Jul. 14, 1997;-   U.S. Pat. No. 5,924,531, which issued on Jul. 20, 1999, from U.S.    patent application Ser. No. 08/721,550, filed Sep. 26, 1996; and-   U.S. Pat. No. 4,909,361, which issued on Mar. 20, 1990, from U.S.    patent application Ser. No. 07/257,070, filed Oct. 13, 1988.

The present disclosure provides even further improved driveshaft dampersand systems and methods for making and using driveshaft dampers.

SUMMARY

The present disclosure embraces driveshaft dampers for use indriveshafts (e.g., vehicle driveshafts, propeller shafts, machinery,etc.) to dampen or attenuate noise, vibration, and harshness (NVH). Thepresent disclosure further embraces systems and methods for making andusing driveshaft dampers. The driveshaft dampers may be formed using ahelical-winding process and may include attenuation strips (e.g.,polymeric retaining members) with a plurality of elongate protrusions(e.g., attenuation tape or ribbon with a plurality of elongateprotrusions configured for interference fit within a driveshaft).

In one aspect, the present disclosure embraces helically-wounddriveshaft dampers including a core or other substantially cylindricalstructure having a plurality of helically-wound plies of a core materialand one or more attenuation strips helically wound around the core. Inexemplary embodiments, the plies of core material (e.g., strips ofpaper, paperboard, or other core materials) may have a width of about 2to 5 inches. An exemplary helically-wound core may exhibit a pitch angleθ (theta) of about 45 to 74 degrees and an outer diameter of betweenabout 3 inches and 5 inches. The attenuation strips typically include aplurality of elongate protrusions (e.g., at least three elongateprotrusions).

In another aspect, the present disclosure embraces attenuation stripsconfigured for making helically-wound driveshaft dampers. Exemplaryattenuations strip may include a plurality of elongate protrusions. Insome exemplary embodiments, the attenuation strips include a baseconfigured to be adhered to a core and elongate protrusions extendingupwardly from the base. Exemplary attenuation strips exhibit abase-to-protrusion ratio BPR of at least 8 and a protrusion-spacingratio PSR between 1 and 5.

In yet another aspect, the present disclosure embraces methods of makingdriveshaft dampers, including helically-wound driveshaft dampers andconvolute driveshaft dampers. Exemplary methods of making driveshaftdampers include helically winding plies of core material around amandrel at a winding angle θ_(w) to form a core, and concurrentlyhelically winding one or more attenuation strips (e.g., a “triple-ridge”attenuation strip) around the core as the core advances longitudinallyalong the mandrel and securing the one or more attenuation strips to thecore at a pitch angle θ. A driving force may be provided to helicallywind the plies of core material and to advance the core materiallongitudinally along the mandrel.

The foregoing illustrative summary, other objectives and/or advantagesof the present disclosure, and the manner in which the same areaccomplished are further explained within the following detaileddescription and its accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

The drawings are provided as examples, may be schematic, and may not bedrawn to scale. The present inventive aspects may be embodied in manydifferent forms and should not be construed as limited to the examplesdepicted in the drawings.

FIG. 1 is a cut-away perspective view of a driveshaft showing anexemplary driveshaft damper installed in the driveshaft.

FIG. 2 depicts an exemplary helically-wound driveshaft damper that hasone attenuation strip with two elongate protrusions helically woundabout the circumference of a core.

FIG. 3 depicts an exemplary helically-wound driveshaft damper that hastwo attenuation strips, each with two elongate protrusions helicallywound about the circumference of a core.

FIG. 4 is an isolated, cut-away view of an exemplary core.

FIG. 5 depicts an exemplary helically-wound driveshaft damper with twoattenuation strips, each having three elongate protrusions helicallywound about the circumference of a core.

FIG. 6 schematically depicts a 360-degree portion of a helical windingincluding two abutting, helically-wound strips.

FIG. 7 schematically depicts the helical winding portion of FIG. 6 in anunwound, flat configuration.

FIGS. 8 and 9 depict exemplary continuous helical-winding processes inwhich a plurality of plies of a core material and one or moreattenuation strips are wound concurrently around a mandrel.

FIG. 10 is a top plan view of a winding machine that may be used to makea helically-wound driveshaft damper.

FIG. 11 is a perspective view of a winding machine that may be used tomake a helically-wound driveshaft damper.

FIG. 12 is a perspective view of another winding machine that may beused to make a helically-wound driveshaft damper.

FIG. 13 is a perspective view of a representative lengthwise portion ofa comparative attenuation strip with one elongate protrusion (i.e., a“single-ridge” attenuation strip).

FIG. 14 is an end elevation view of the comparative, single-ridgeattenuation strip of FIG. 13 .

FIG. 15 is a perspective view of a representative lengthwise portion ofan exemplary attenuation strip with two elongate protrusions (i.e., a“double-ridge” attenuation strip).

FIG. 16A is an end elevation view of the attenuation strip of FIG. 15 .

FIGS. 16B and 16C are alternative, exemplary embodiments an attenuationstrip with two elongate protrusions (i.e., a “double-ridge” attenuationstrip).

FIG. 17 is a perspective view of a representative lengthwise portion ofan exemplary attenuation strip with three elongate protrusions (i.e., a“triple-ridge” attenuation strip).

FIG. 18 is an end elevation view of the attenuation strip of FIG. 17 .

FIG. 19 is a cross-sectional view of an exemplary driveshaft damper withtwo attenuation strips each having a plurality of elongate protrusionshelically wound about the circumference of a core.

FIGS. 20-22 are isolated, end elevational views of additional exemplaryattenuation strips, each in a flat configuration.

FIGS. 23-25 are isolated, top plan views of additional exemplaryattenuation strips, each in a flat configuration.

FIGS. 26 and 27 are isolated views of the exemplary driveshaft damper ofFIG. 1 , which includes a single-start “triple-ridge” attenuation strip.

FIG. 28 depicts the exemplary driveshaft damper of FIG. 5 , whichincludes dual-start “triple-ridge” attenuation strips.

FIG. 29 depicts an exemplary driveshaft damper having a single-start“triple-ridge” attenuation strip with outer surficial foam.

FIGS. 30 and 31 depict the damper of FIG. 29 installed in a driveshaft.

FIGS. 32 and 33 depict an exemplary driveshaft dampers with internalsurficial foam.

FIGS. 34-36 depict dampening mechanisms provided by exemplary driveshaftdampers.

FIGS. 37-41 are isolated views of cores (e.g., paper or paperboardcores).

FIG. 42 depicts an exemplary driveshaft damper including an outerwrapping layer.

FIG. 43 is a cross-sectional view taken along line 43-43 of FIG. 42 .

FIG. 44 depicts a frequency-response plot for an empty aluminumpropshaft tube.

FIG. 45 is a frequency-response plot for a comparative driveshaftdamper.

FIGS. 46-47 are frequency-response plots for exemplary driveshaftdampers having dual-start “triple-ridge” attenuation strips.

FIGS. 48-49 depict frequency-response plots for comparative driveshaftdampers.

FIG. 50 is a frequency-response plot for an exemplary driveshaft damperhaving a single-start “triple-ridge” attenuation strip.

FIG. 51 is a frequency-response plot for an exemplary driveshaft damperhaving dual-start “triple-ridge” attenuation strips.

FIGS. 52 and 53 depict frequency-response plots for exemplary driveshaftdampers having a single-start “triple-ridge” attenuation strip withsurficial foam.

FIGS. 54-58 depict frequency-response plots for exemplary driveshaftdampers having either a single-start “double-ridge” attenuation strip ordual-start “double-ridge” attenuation strips.

FIGS. 59 and 60 depict frequency-response plots for the combination oftwo different kinds of driveshaft dampers.

FIG. 61 is a frequency-response plot for a comparative foam-slugdriveshaft damper.

FIG. 62 is a frequency-response plot for an empty steel propshaft tube.

FIG. 63 is a frequency-response plot for a comparative driveshaftdamper.

FIG. 64 is a frequency-response plot for an exemplary driveshaft damperhaving a single-start “triple-ridge” attenuation strip.

FIG. 65 is a frequency-response plot for an exemplary driveshaft damperhaving dual-start “triple-ridge” attenuation strips.

FIG. 66 is a frequency-response plot for the combination of twodifferent kinds of driveshaft dampers.

FIG. 67 depicts a frequency-response plot for an empty aluminumpropshaft tube.

FIGS. 68-72 depict frequency-response plots for comparative driveshaftdampers.

FIGS. 73-74 depict an exemplary driveshaft damper having a single-start“triple-ridge” attenuation strip with outer surficial foam andsurface-indicia.

DETAILED DESCRIPTION

In this detailed description, various aspects and features are hereindescribed with reference to the accompanying figures. These aspects andfeatures generally pertain to driveshaft dampers for use in driveshaftsto dampen or attenuate noise, vibration, and harshness (NVH), and tosystems and methods for making and using driveshaft dampers. Exemplarydriveshaft dampers include helically-wound driveshaft dampers having oneor more attenuation strips (e.g., attenuation tape-like structures, suchas elastomeric attenuation strips) helically wound around a core orother substantially cylindrical structure. The core may be formed from aplurality of plies of helically-wound core material laminated with anadhesive.

Specific details are set forth to provide a thorough understanding ofthe present disclosure. It will be apparent, however, to those havingordinary skill in the art that the disclosed driveshaft dampers,systems, and methods may be performed without some or all of thesespecific details. As another example, features disclosed as part of oneembodiment can be used in the context of another embodiment to yield afurther embodiment. In some instances, well-known aspects have not beendescribed in detail to avoid unnecessarily obscuring the presentdisclosure. This detailed description is therefore not to be taken in alimiting sense, and it is intended that other embodiments are within thespirit and scope of the present disclosure.

FIG. 1 is a schematic, cut-away, perspective view of a driveshaft 10showing an exemplary driveshaft damper 20 installed therein, inaccordance with an embodiment of this disclosure. In FIG. 1 , anintermediate, lengthwise portion of the driveshaft 10 is cut away toshow a portion of the damper 20 that is normally hidden from view withinthe driveshaft. Those having ordinary skill in the art will appreciatethat the driveshaft 10 may be configured for use with any number ofvarious applications. As examples, a dampened tubular driveshaft 10 witha driveshaft damper 20 frictionally secured therein may be provided for:automotive powertrains such as those commonly used in cars, trucks,tractors, all-terrain vehicles, rolling stock, heavy machinery; marinepowertrains, such as those commonly used in boats and other marinevessels and aquatic machinery; and industrial machinery in amanufacturing facility or processing plant. Generally, a driveshaftdamper 20 will be installed in a hollow region of a tubular driveshaft10 as depicted in FIG. 1 . Such a driveshaft damper 20 may be installedin any suitable driveshaft, such as a main driveshaft or a half shaft.For example, a vehicle may have a main driveshaft that transfers powerto a main drive axle and a half shaft that transfers power to anauxiliary drive axle. The main drive axle may be configured to transferpower to the rear wheels and the auxiliary drive axle may be configuredto transfer power to the front wheels, or vice versa.

During normal vehicle operation, internal factors within the operationof the vehicle's transmission and rear axle (e.g., gear mesh, axlewhine, and clutch clunk), along with external factors (e.g., operationalvehicle speed, operational vehicle load, or critical vehicle speed), cancause excitation of the driveshaft 10 (e.g., the propshaft tube),thereby amplifying NVH. Resonance dampers 20 can limit the intensity(dB) of various noises at the propshaft's natural resonance frequencywhen aggregated with vehicle noise occurring at those frequencies.Resonance dampers 20 can sometimes shift frequencies away fromproblematic natural resonance frequencies. Those having ordinary skillin the art will appreciate that some frequencies (e.g., about 600 Hz inaluminum propshafts 10) are more problematic than others, such thatelevated resonance at some frequencies is not necessarily a problemuntil external factors or operational factors work together to amplifyNVH.

With continued reference to the example depicted in FIG. 1 , arepresentative driveshaft damper 20 typically includes a core 22 and atleast one attenuation strip 24 helically wound about the circumferenceof the core (or the perimeter of a non-circular core). The embodimentdepicted in FIG. 1 is a helically-wound driveshaft damper 20 thatincludes a single attenuation strip 24 mounted on the outer surface of acylindrical core 22. The core 22 may be formed by helically winding aplurality of plies of core material. The one or more attenuation strips24 may be helically wound around the core 22 concurrently with thewinding of the plies of core material. Multiple plies of helically-woundcore material may be adhesively laminated together to form the core 22.Alternatively, a core 22 may be formed using any other suitable methods,including rolling plies of core material to form a convolute tube, orextruding, pressing, or milling a core material to form a unitary core.In addition, various other driveshaft damper configurations are withinthe spirit and scope of the present disclosure.

NVH can sometimes be transmitted or amplified to other components, suchas into the passenger cabin of a vehicle. The driveshaft damper 20 helpsdampen or attenuate NVH associated with the driveshaft 10 and relatedequipment (not shown) to provide for quieter and smoother operation, toreduce wear and tear, and to improve operator comfort. The respectiveNVH components emanating from an engine, a transmission, a rear axle, orother powertrain or drivetrain components may resonate to the driveshaft10. Even low levels of NVH may become dramatically amplified in thedriveshaft 10 because of structural resonance or acoustic resonance,which can occur when the frequency of respective NVH components match aresonance frequency of the driveshaft 10. Likewise, NVH componentsresonating in (or emanating from) the driveshaft 10 may further resonateto adjacent components or supporting structures. Here again, even lowlevels of NVH resonating in (or emanating from) the driveshaft 10 maybecome dramatically amplified because of structural resonance oracoustic resonance of such adjacent components or supporting structures.

A driveshaft damper 20 with desired damping and attenuationcharacteristics may be formed using one or more core materials andattenuation strips 24 as disclosed herein. Both the properties andconfiguration of the core 22 and attenuation strips 24 may affectdamping and attenuation characteristics of a driveshaft damper 20.Without being bound to any theory, it is thought that various featuresof a driveshaft damper 20 and its respective components affect NVHdamping and attenuation performance factors. For example, thecomposition and configuration of a driveshaft damper 20 affect dampingperformance factors such as damping ratio c (zeta), Q factor, andlogarithmic decrement 6 (delta). Additionally, such aspects affectattenuation performance factors such as attenuation coefficient α(alpha). Such aspects include the nature and extent of the contactsurface engaging with the inner surface of the driveshaft 10, the sizeand mass of the core 22, and the physical properties of the corematerial and attenuation strips 24.

In one aspect, a driveshaft damper 20 may be configured to operate as apassive damper, damping or attenuating NVH by absorbing energy fromvarious components of NVH. For example, the core 22 of a driveshaftdamper 20 formed from suitable materials will typically have a lowerresonance frequency than that of a driveshaft 10, and as such, the core22 isolates higher frequency NVH in the driveshaft.

In another aspect, a driveshaft damper 20 may be configured to operateas a dynamic absorber or tuned mass damper (e.g., the terms “dynamicabsorber” and “tuned mass damper” are used herein interchangeably exceptwhere context requires). For example, the attenuation strips 24 may beconfigured to allow the core 22 to oscillate with a desired phase shiftwith respect to a resonance frequency of one or more NVH components.Various aspects of the driveshaft damper 20 can be configured asdisclosed herein to obtain desired operability as a passive damperand/or as a dynamic absorber.

The core 22 of a driveshaft damper typically may be made from papermaterial (e.g., paperboard), although other suitable core material maybe used in addition or as an alternative to paper material. For example,core materials may include, individually or in combination, variouskinds of paperboard or other paper materials (e.g., treated paper-likematerials, such as parchment paper, wax paper, or polymeric film orsheet), particle board materials, fiberboard materials, engineered woodmaterials, polymeric materials, plastic materials, engineered plasticmaterials, fiber-reinforced polymer materials, metal or metal alloymaterials, carbon fiber materials, fiberglass materials, and ceramicmaterials (e.g., flexible ceramic). Any of these materials orcombinations of these materials may be formed into a core 22 using anysuitable method, including rolling plies of core material (e.g., paperplies) to form a helically-wound or convolute tube, or extruding,pressing, or milling a core material to form a unitary core. In someembodiments, a core 22 may be formed from multiple plies of corematerial, laminated together using an adhesive, such as emulsionadhesives (e.g., polymer dispersion adhesives and solvent-basedadhesives), pressure-sensitive adhesives, contact adhesives, andthermoplastics. In some embodiments, a core 22 may be formed frommultiple plies of core material wound around a unitary core in a helicalor convolute manner.

The attenuation strips 24 (e.g., retaining members) are typically formedfrom a suitable elastomeric material, such as natural or syntheticrubber (e.g., extruded rubber). The elastomeric material may have aShore hardness between 20 and 100 Shore A durometer (e.g., 30 to 80Shore A hardness) in accordance with ASTM D 2000. In accordance with thepresent disclosure, durometer of the elastomeric material may be chosento modify the damping characteristics of the driveshaft damper 20 (e.g.,to reduce or to shift resonance frequencies). Exemplary materials forthe attenuation strips 24 include ethylene propylene diene monomer(EPDM) rubber (e.g., 55+/−5 Shore A durometer), hydrogenated nitrilebutadiene (HNBR), silicone rubber (e.g., 20-80 Shore A durometer, suchas 45-55 Shore A durometer), and thermoplastic elastomer (TPE) material.The attenuation strips 24 are typically extruded to yield a unitarysolid (e.g., extruded EPDM or silicone rubber). For example, a siliconerubber that is suitable for forming heat-resistant attenuation strips 24is available from Timco Rubber Products, Inc. as 50 DUROMETER SILICONE.In an alternative embodiment, the elastomeric materials are aeratedduring extrusion or otherwise modified to form a closed-cell rubber foam(e.g., rubber sponge). One or more attenuation strips 24 are typicallysecured to a core (e.g., a paperboard core) about its circumference toform a driveshaft damper. As noted, the attenuation strips 24 may besecured to the core using an adhesive, such as emulsion adhesives (e.g.,polymer dispersion adhesives and solvent-based adhesives),pressure-sensitive adhesives, contact adhesives, and thermoplastics.

The attenuation strips 24 are typically configured so predeterminedportions (e.g., contact surfaces) of the attenuation strips frictionallyengage with the inner surface of the driveshaft 10 in a predeterminedmanner. This both frictionally secures the driveshaft damper 20 inposition within the tubular driveshaft 10 via interference fit and atleast partially provides a spring rate of the driveshaft damper. Thesecure engagement and spring rate are cooperatively configured in amanner that allows the driveshaft damper 20 to provide good NVH dampingor attenuation.

With continued reference to the example depicted in FIG. 1 , theattenuation strips 24 may include at least one contact surface and atleast one non-contact surface. A contact surface refers generally to anyportion of an attenuation strip 24 (e.g., an outer portion of anelongate ridge or protrusion 26) that securely contacts the innersurface of the driveshaft 10. A non-contact surface refers generally tothe portions of the base 28 of the attenuation strip 24 (or structuressupporting the elongate protrusions 26) between or otherwise near theengageable elongate protrusions. The nature and extent of the contactsurfaces may be configured to obtain desired damping or attenuationcharacteristics. For example, the number and configuration of theattenuation strips 24 may be configured to allow a desired oscillationunder certain operating conditions of the driveshaft 10. In someembodiments, NVH damping/attenuation and oscillation performance factorsmay be augmented by increasing or decreasing the number of contactsurfaces (e.g., outer portions of the protrusions 26) of the attenuationstrips 24 engaging the inner surface of the driveshaft 10. For example,the number and arrangement of the elongate protrusions 26 may beconfigured as disclosed herein.

To achieve effective NVH damping, the contact surfaces of theattenuation strips 24 (e.g., the outer portions of the elongateprotrusions 26) are typically configured for significant interferencefit (e.g., substantial frictional fit) within a driveshaft or propshaft10.

With respect to an attenuation strip 24, the term “significantinterference fit” means that a contact surface of the attenuation stripis in forced engagement with the inner surface of the driveshaft 10 andrequires more than mere touching. For example, the term “significantinterference fit” embraces elongate-protrusion displacement (e.g.,strain, such as bending, resulting from the interference fit reducingthe height of an elongate protrusion 26 by at least 10 percent (e.g.,about 15 percent) of the maximum height of an elongate protrusion (e.g.,a 0.25-inch elongate protrusion displaced by at least 0.025 inch whenfrictionally fit within a driveshaft 10), typically at least 20 percent(e.g., strain resulting from the interference fit reducing the height ofan elongate protrusion by about 25 percent) of the maximum height of anelongate protrusion (e.g., a 0.25-inch elongate protrusion displaced byat least 0.05 inch when frictionally fit within a driveshaft), and moretypically at least 30 percent (e.g., strain resulting from theinterference fit reducing the height of an elongate protrusion by about35-50 percent) of the maximum height of an elongate protrusion (e.g., a0.25-inch elongate protrusion displaced by at least 0.075 inch whenfrictionally fit within a driveshaft). This concept ofelongate-protrusion displacement embraces the reduction in the height ofthe elongate protrusion 26 when a driveshaft damper 20 is installed viainterference fit within a driveshaft or propshaft 10.

Similarly, with respect to a driveshaft damper 20 having an exemplaryattenuation strip 24, the term “significant interference fit” means thata contact surface of the driveshaft damper (e.g., an attenuation stripwith elongate protrusions 26) is in forced engagement with the innersurface of the driveshaft 10 (i.e., more than mere surficial touching).For example, for exemplary driveshaft dampers 20 having outermostdiameters of between about 3 inches and 6 inches, the term “significantinterference fit” embraces an interference fit having the effect ofreducing the outer diameter of the damper by over 2 percent (e.g.,between about 2.5 and 5 percent) of the driveshaft damper's diameter.Typically, on a percentage-of-diameter basis, driveshaft dampers 20 withsmaller diameters are configured to have a larger percentageinterference fit than driveshaft dampers with somewhat larger diameters(e.g., a 100-mil interference fit for a 3-inch diameter driveshaftdamper as compared with a 120-mil interference fit for a 6-inch diameterdriveshaft damper).

Various different embodiments are depicted in the drawings of thisdisclosure and discussed herein. The disclosed embodiments may be alike,except for variations noted and variations that will be apparent tothose of ordinary skill in the art. For ease of understanding, similarreference numerals are used for features having at least somesimilarity, with the reference numerals being incremented by 100 fromembodiment to embodiment.

FIG. 2 depicts a cut-away length of an exemplary helically-wounddriveshaft damper 120 that has one attenuation strip 124 with twoelongate protrusions 126 helically wound about the circumference of acore 122, in accordance with another embodiment of this disclosure. Moregenerally with reference to FIG. 2 , in an exemplary helically-wounddriveshaft damper 120, one or more attenuation strips 124 helically windabout the circumference of a core 122 at a pitch angle, θ (theta). Forconvention, pitch angle is measured as the acute angle characterizedaccording to this equation:

$\begin{matrix}{{\theta = {\arctan\left( \frac{\pi D}{L} \right)}},} & \left( {{eq}.1} \right)\end{matrix}$where L is a pitch length representing the lateral distance betweenwindings at a given cross-sectional radian of the resulting core 122 andD is the outer diameter of the resulting core. The pitch angle θ ismeasured from the longitudinal axis of the tubular core 122. As such, asteeper pitch angle θ corresponds to a shorter pitch length L. As willbe discussed in greater detail (below), in a given damper 120, each ofthe one or more attenuation strips 124 and the strips that form the core122 (e.g., core plies) may all have the same pitch angle θ, althoughvariations are within the scope of this disclosure.

A dimensionless pitch ratio P may be characterized according to thisequation:

$\begin{matrix}{P = {\frac{{core}{diameter}}{{pitch}{length}}.}} & \left( {{eq}.2} \right)\end{matrix}$Driveshaft dampers 120 made using a typical helical-winding process mayexhibit a pitch ratio P between 0.7 and 1.0. For example, a core 122having a diameter D of 3.5 inches wound from plies of core material 4.3inches wide provides a winding angle θ_(w) of about 67 degrees, whichyields a pitch length L of about 4.7 inches and a pitch ratio P of about0.75. The pitch ratio P can be modified (e.g., increased) somewhat, byadjusting (e.g., decreasing) the width of the plies of core material.For a core 122 having a diameter D of 3.5 inches, however, the plies ofcore material typically would not be decreased to less than 3.2 incheswide. Core material with a width of 3.2 inches provides a winding angleθ_(w) of 73 degrees, which yields a pitch length of about 3.3 inches,and a pitch ratio P of about 1.0.

Without being bound to any theory, it is thought that in someembodiments a driveshaft damper 120 having an attenuation strip may beconfigured to provide improved NVH damping or attenuation by increasingthe pitch ratio P, which in turn increases the attenuation-strip contactsurface engaging the inner surface of the driveshaft 10 (FIG. 1 ). Thiscan be achieved, for example, by increasing the pitch ratio P of theattenuation strips 124. In some embodiments, an increase in theattenuation-strip contact surfaces engaging the inner surface of thedriveshaft 10 can advantageously increase the spring rate of thedriveshaft damper 120. The attenuation strips 124 may allow thedriveshaft damper 120 to function as a dynamic absorber. Additionally,the attenuation strips 124 may modify the resonance frequency of thedriveshaft damper 120.

When using a conventional continuous helical-winding process tosimultaneously form a core 122 and mount one or more attenuation strips124 on the core, the pitch angle θ of the attenuation strips follows(e.g., is typically about the same as) the pitch angle of the corematerial (e.g., the winding angle θ_(w) of paper strips that form ahelically-wound, paper-tube core). Pitch angle θ is limited by factorsassociated with both manufacturing conditions and structuralrequirements of the core 122. For example, and as will be discussed ingreater detail (below), with a typical continuous helical-windingprocess, a helically-wound core 122 is formed on a mandrel. A drivingforce is supplied both to wind core material helically around a mandreland to advance the core material longitudinally along the mandrel as thecore is formed. Such a helical-winding process may employ a serpentinebelt configured to supply a rotational force to wind the core material,as will be discussed in greater detail (below). The rotating corematerial translates a lateral force to advance the resulting core 122longitudinally along the mandrel. In such processes, core materialadvances along the mandrel at a rate that may be characterized by thelateral distance advanced per helical revolution of the core material.

Without being bound to any theory, if the pitch angle θ (i.e., thewinding angle θ_(w)) is too small or too large, the core material willnot properly advance along the mandrel because of insufficienttranslational lateral driving force. In addition, if the pitch angle θ(i.e., the winding angle θ_(w)) is too small or too large, the corematerial will not properly wind helically around the mandrel andtranslational lateral forces may exceed the shear strength of the corematerial at its interface with the mandrel, leading to runnabilityissues with helical-winding machines.

Additionally, increasing pitch angle θ requires a corresponding decreasein the width of the core material helically wound to form the core, andstructural characteristics of the core 122 depend on the width of thecore material. If the core material (e.g., a paper attenuation strip) istoo narrow or too wide, the resulting core 122 may lack sufficientstructural integrity. Additionally, helical-winding machines may exhibitfurther runnability issues with core materials that are too narrow ortoo wide because of an increasing tendency to tear under tension forcesinherent in the winding process.

FIG. 2 depicts a representative driveshaft damper 120 formed using atypical helical-winding process. FIG. 2 schematically depicts that thecore 122 was formed from a plurality of plies of core material because,for example, a butt joint (e.g., a seam) defined between inner plies isschematically represented by a helical dashed line in FIG. 2 . In theembodiment depicted in FIG. 2 , one elastomeric attenuation strip 124 ishelically wound about the circumference of the core 122 (i.e., asingle-start configuration). The attenuation strip 124 has two elongateprotrusions 126. As shown, the 122 core has a diameter D, and theattenuation strip 124 winds helically around the circumference of thecore at a pitch angle θ.

Typically, the core material and the attenuation strips 124 have acommon pitch angle when using a continuous helical-winding process inwhich the plies of core material and the one or more attenuation stripsare wound concurrently around a mandrel. When concurrently winding pliesof core material and one or more attenuation strips 124, the plies ofcore material and the attenuation strips may be introduced along themandrel in close longitudinal proximity to one another or at positionslongitudinally offset along the length of the mandrel. As the plies ofcore material and the attenuation strips 124 are wound helically aroundthe mandrel, the resulting helically-wound core 122 or driveshaft damper120 advances longitudinally along the mandrel. The advancement ratedepends on the pitch angle θ and the linear speed of the serpentine beltthat supplies a rotational force to wind the core material.

The helical windings exhibit a pitch length L, which may be measuredlongitudinally from any selected position on the plies of core materialor on the one or more attenuation strips 124. For example, a centerlineor a lateral edge of a ply or strip (or of an elongate protrusion 126)may be used as a reference point when measuring pitch length L. Assimilarly depicted in FIG. 2 , a gap G exists between adjacent lateraledges of the attenuation strip 124, and the width of the gap G may bemeasured along the longitudinal axis of the driveshaft damper 120. Asdepicted in FIG. 2 , the pitch length L for either elongate protrusion126 is greater than the gap G between the attenuation strip's adjacentlateral edges.

In exemplary embodiments (e.g., as depicted in FIG. 2 ), an attenuationstrip 124 includes a base 128 having adhesion flanges 130 extending fromopposite sides thereof to assist with adhering the attenuation strip tothe core 122. In the embodiment depicted in FIG. 2 , outer ends of theadhesion flanges 130 are beneath at least one outer layer 132 ofmaterial overlapping the respective adhesion flanges on respective sidesof the attenuation strip 124. The extent of the adhesion flanges 130beneath the overlapping material 132 may vary.

In some embodiments, the overlapping material 132, if present, may be anadditional ply of core material, or another kind of material selectedfrom among the core materials discussed herein. The additional ply ofoverlapping material 132 (e.g., a paper “hold-down” ply 132) may beincluded to mechanically secure the attenuation strip 124 to the core122. In this regard, although the single-start, dual-protrusionattenuation strip 124 is bonded by adhesive material to the core 122,adhesive bonds can fail. An optional “hold-down” ply 132 provides anadditional mechanism to secure the dual-protrusion attenuation strip 124to the core. Failure of the adhesive bond between the attenuation strip124, even with its adhesion flanges 130 on either side of the twoprotrusions 126, and the core 122 can cause the attenuation strip toseparate from the core. Such delamination failure of the driveshaftdamper 120 could cause rattling within the propshaft or hinder thereduction of NVH, such as by changing the oscillation rate and/orshifting the resonance frequency of the driveshaft tube. Suchdelamination failure seems less likely as the width of the attenuationstrip 124 increases, thereby providing more bonding area between theattenuation strip and the core. For example, comparative retainingmembers, such as disclosed in commonly assigned U.S. Pat. No. 4,909,361,are typically narrow (e.g., less than 1 inch or so), thereby providinglimited bonding area and necessitating the application of an outer,reinforcing corrugated winding.

The width of the “hold-down” ply 132 is typically selected to overlapadjacent adhesion flanges 130 of the dual-protrusion attenuation strip124 as helically wound around the core 122. In this regard, the width ofthe “hold-down” ply 132 is necessarily slightly greater than gap G,which exists between adjacent lateral edges of the attenuation strip124. For example, a gap G of 1 inch might require a 1.25-inch“hold-down” ply, and a gap G of 2 inches might require a 2.25-inch“hold-down” ply. When the “hold-down” ply 132 is bonded to the core 122,the respective edge portions of the “hold-down” ply overlap the adjacentadhesion flanges 130 of the dual-protrusion attenuation strip 124,thereby mechanically securing the dual-protrusion attenuation strip 124to the core 122 (i.e., the “hold-down” ply is typically not bonded tothe top portions of the adhesion flanges). In effect, a “hold-down” ply132 provides an additional mechanism to ensure the attenuation strip 124is an integral part of the driveshaft damper 120.

In another embodiment, the overlapping material 132 may includepolyether foam or other damping material (e.g., a polymeric batting or apolymeric nonwoven). For example, additional overlapping material can bepositioned upon a “hold-down” ply 132 or used in lieu of a “hold-down”ply.

When configuring a core 122 for use in a driveshaft damper 120,trigonometry determines a winding angle θ_(w) for the helically-woundplies of core material. The winding angle θ_(w) generally depends on thewidth of the core material and the diameter of the core 122. Thediameter of the core 122 can be based, for example, either on themandrel around which the plies of core material will be helically wound(e.g., the inner diameter of the resulting core) or, more typically, onthe desired outer diameter of the resulting core. Unless otherwisespecified, the winding angle θ_(w) and the pitch angle θ are specifiedfor the outer diameter D of the core, and the strip width w is specifiedfor the outer ply of core 122 (e.g., the outermost strip of paperforming the core).

The width of the core material and the diameter of the core 122 may beselected based on (i) process considerations, including runnability,productivity, or practical limitations of the helical-winding machine,and/or (ii) performance considerations, including structuralrequirements of the core, the planned use of the resulting driveshaftdamper 120, and the damping and attenuation performance of thedriveshaft damper (e.g., greater damper mass). For a given corematerial, the thickness and density of the core 122, as well as theselected core material and the width of the plies of core material, allcorrelate to the resulting core's structural integrity. As examples,structural integrity of a core 122 may be characterized by axialcompression strength, lateral compression strength, or radialcompression strength. Additionally, even if a given winding angle may bemathematically possible, there are practical limitations to the range ofwinding angles that can be achieved on a conventional helical-windingmachine to form a core 122 having a desired set of physical propertiesand structural integrity characteristics.

Given the width w of the plies of core material, the core winding angleθ_(w) for the plies may be determined using this equation:

$\begin{matrix}{{\theta_{w} = {\arccos\left( \frac{w}{\pi D} \right)}},} & \left( {{eq}.3} \right)\end{matrix}$where D is the outer diameter of the resulting core 122. A resultingcore pitch length L_(w) may be calculated from the core winding angleθ_(w) and the width w of the core material using this equation:

$\begin{matrix}{L_{w} = {\frac{w}{\sin\theta_{w}}.}} & \left( {{eq}.4} \right)\end{matrix}$As noted, the strip width w references the outer ply of core material(e.g., the outermost paper strip) where different ply-widths areemployed.

Typically, the core winding angle θ_(w) will allow a given ply of corematerial to helically wind around the mandrel without overlapping uponitself. Overlapping may cause an uneven surface, which may compromisethe quality of the resulting core 122 or driveshaft dampers 120 madefrom such a core. The winding angle θ_(w) may provide for a nominal seamgap. As an example, the option of a butt joint or a seam gap isschematically represented by a helical dashed line in FIG. 2 . Seam gapsare discussed in greater detail (below) with reference to FIG. 4 . Ifthe ply width remains constant, the seam gap will widen as the diameterof the resulting core 122 increases with successive plies of corematerial. To control seam-gap widening during core construction, theinitial plies of core-material strips (i.e., the inner plies) arenarrower than the final, outer plies of core-material strips (i.e., theouter plies). For example, the inner paper ply might be a 4.5-inch stripwhile the outer paper ply might be a 4.625-inch strip. In this example,the paper width w would be reported as 4.625 inches with respect to thepaper-tube core 122. When using a typical continuous helical-windingprocess, the pitch angle θ of the one or more attenuation strips 124matches the winding angle θ_(w) of the plies of core material. (If thepitch angle θ of an attenuation strip 124 were to differ from thewinding angle θ_(w) of the plies of core material, then thehelically-wound attenuation strip would advance along the mandrel at arate differing from the rate of the helically-wound plies of corematerial. In addition, a mismatch between pitch angle θ of the one ormore attenuation strips 124 and the winding angle θ_(w) of the plies ofcore material might lead to poor interfacial contact and/or poor bondingof the one or more attenuation strips to the core 122.) In accordancewith the present disclosure, the winding angle θ_(w) of the plies ofcore material and the corresponding pitch angle θ of the one or moreattenuation strips 124 may be chosen to modify the dampingcharacteristics of the driveshaft damper 120 (e.g., to reduce or shiftresonance frequencies) as installed in a particular propshaft, subjectto the operating capabilities of a helical-winding machine.

In this regard, a desired pitch length L for the one or more attenuationstrips 124 (e.g., the corresponding spacing between adjacent attenuationstrips) may be selected based at least in part on resulting dampingattenuation performance of the driveshaft damper 120. For example, apitch length L that corresponds to a resulting pitch ratio P (i.e., corediameter D÷pitch length L) may be desired. In some embodiments,increasing pitch ratio P to increase the contact surfaces engaging theinner surface of the driveshaft may be desired. Accordingly, adriveshaft-damper configuration may start from a desired pitch length L(or pitch ratio P) of the one or more attenuation strips 124, and workbackward to determine a corresponding pitch angle θ for the attenuationstrips or winding angle θ_(w) of the plies of core material and,finally, the corresponding width for the strips of core material. Thewidth of the core material and the corresponding winding angle θ_(w) areconfigured to avoid constraints associated with runnability,productivity, or practical limitations of the helical-winding machine,and/or structural requirements or other properties of the core 122 whilemeeting the desired pitch length L or pitch ratio P.

Consequently, when using a typical continuous helical-winding process,the pitch length L of the attenuation strips 124 and corresponding pitchangle θ or pitch ratio P tend to be limited by constraints associatedwith the helical-winding process and the required properties of the core122. For example, in some embodiments, a pitch angle θ that would yielda desired damping or attenuation performance may be incompatible withconstraints associated with runnability, productivity, or practicallimitations of a helical-winding machine, and/or structural requirementsor other properties of the core 122 or dimensional configurationsrequired by the particular application in which the driveshaft damper120 will be used.

In some representative embodiments, an additional attenuation strip 124may be added (e.g., a two-start configuration) to achieve an effectivepitch angle θ_(e) that exceeds the winding angle θ_(w) of the corematerial. However, the space available for additional attenuation strips124 typically is limited by the width of the attenuation strips (e.g.,the base's wider adhesion surface), because it is generally undesirablefor attenuation strips to overlap one another or to overlap a seam gap.Such overlapping can cause an uneven surface that compromises theadhesion of attenuation strips 124 to the core 122, and/or interfereswith proper fit of the driveshaft damper 120 inside a driveshaft.Moreover, if a narrow attenuation strip (e.g., less than 1 inch) isbonded to the core 122 at a seam, a weak bond results between the coreand the attenuation strip, even with its adhesion flanges on either sideof the protrusion. A weak bond can cause the attenuation strip toseparate from the core, especially if the driveshaft damper is cutduring manufacturing where the attenuation strip is positioned over aseam. (As discussed herein, a helically-wound paper tube is typicallyformed continuously during the manufacture of driveshaft dampersaccording to the present disclosure.) This can lead to delaminationfailure of the driveshaft damper when the driveshaft damper is insertedinto a propshaft tube.

FIG. 3 depicts a representative driveshaft damper 220 with twoattenuation strips 224, 225 (i.e., a dual-start configuration of“double-ridge” attenuation strips), in accordance with anotherembodiment of this disclosure. The driveshaft damper 220 has a core 222formed of a plurality of plies of core material and two attenuationstrips 224, 225 helically wound about the circumference of the core. Thetwo attenuation strips 224, 225 are offset from one another by 180degrees around the perimeter (e.g., the circumference) of the core 222.Thus, the driveshaft damper 220 may include a first attenuation strip224 starting at 0 degrees and a second attenuation strip 225 starting at180 degrees. For each of the first and second attenuation strips 224,225, the helical winding of the attenuation strip provides a pitchlength L. Together, the first attenuation strip 224 and the secondattenuation strip 225 provide an effective pitch length L_(e), which maybe characterized according to this equation:

$\begin{matrix}{L_{e} = {\frac{{pitch}{length}L}{{number}{of}{elongate}{protrusions}{in}{damper}}.}} & \left( {{eq}.5} \right)\end{matrix}$

In determining effective pitch length L_(e), only elongate protrusions226 that are configured to provide significant interference fit within adriveshaft or a propshaft (e.g., 10-20 percent or moreelongate-protrusion displacement) ought to be considered. Elongateprotrusions 226 configured for forced frictional engagement within adriveshaft or a propshaft (see, e.g., shaft 10 of FIG. 1 ) effect betterNVH reduction. Effective pitch length L_(e) characterizes the length ofattenuation strip (e.g., silicone or EPDM rubber), which helps providethe driveshaft damper 220 with substantial frictional fit within thedriveshaft or propshaft.

The two helically-wound attenuation strips 224, 225 typically provide atleast a narrow gap G, which may be measured longitudinally betweenadjacent lateral edges of the respective attenuation strips. When one orboth attenuation strips 224, 225 have adhesion flanges 230, the gap Gmay be measured longitudinally as between respective adjacent lateraledges of the adhesion flanges or other lateral edges of the attenuationstrips as configured.

The driveshaft damper 220 depicted in FIG. 3 includes adhesion flanges230 on both attenuation strips, without a layer of core material, or thelike, overlapping the adhesion flanges. Alternatively, the gap G may bewider, and a hold-down ply (see, e.g., hold-down ply 132 of FIG. 2 ), orthe like, may be mounted to the core 222 and overlap the respectiveadhesion flanges 230 on respective sides of the attenuation strips 224,225. The extent of the adhesion flanges 230 beneath any overlappingmaterial (see, e.g., hold-down ply 132 of FIG. 2 ) may vary.

In some two-start damper embodiments, the overlapping hold-down material(see, e.g., hold-down ply 132 of FIG. 2 ), if present, may be anadditional ply of core material (e.g., paper) or another kind ofmaterial selected from among the core materials discussed herein. Theadditional ply of core material (e.g., a paper “hold-down” ply) may beincluded to mechanically secure the attenuation strips 224, 225 to thecore. In this regard, although the two dual-protrusion attenuationstrips 224, 225 are bonded to the core 222, adhesive bonds can fail. Ifthere is sufficient space between the adjacent attenuation strips 224,225, an optional “hold-down” ply can provide an additional mechanism tosecure the dual-protrusion attenuation strips to the core. Typically, agap G of at least about 1 inch is necessary to include a “hold-down” plywhile maintaining winding-machine runnability. Failure of the adhesivebonds between the attenuation strips 224, 225, even with the adhesionflanges 230 on either side of the respective protrusions 226, and thecore 222 can lead to the attenuation strips separating from the core222. Such delamination failure of the two-start driveshaft damper 220could cause rattling within the propshaft or hinder the reduction of NVH(e.g., by changing the oscillation rate and/or shifting the resonancefrequency of the driveshaft tube). As noted, such delamination failureseems to be less likely as the width of each attenuation strip 224, 225increases, thereby providing more bonding area between the attenuationstrip and the core 222.

In the two-start configuration depicted in FIG. 3 , the two attenuationstrips 224, 225 are offset from one another by 180 degrees. The width ofany “hold-down” ply is selected to overlap adjacent adhesion flanges 230of the dual-protrusion attenuation strips 224, 225 as helically woundaround the core 222. In this regard, the width of any “hold-down” ply isnecessarily slightly greater than the gap G, which exists betweenadjacent lateral edges of the respective attenuation strips 224, 225.When any “hold-down” ply is bonded to the core 222, the respective edgeportions of the “hold-down” ply overlap the adjacent adhesion flanges230 of two dual-protrusion attenuation strips 224, 225, therebymechanically securing the dual-protrusion attenuation strips 224, 225 tothe core 222 (i.e., the “hold-down” ply is typically not bonded to thetop portions of the adhesion flanges). In effect, a “hold-down” ply, ifpresent, provides an additional mechanism to ensure the attenuationstrips 224, 225 are an integral part of the driveshaft damper 220.

As noted, helical-winding machines may exhibit runnability issues withcore materials that are too narrow or too wide. For two-start damperembodiments (see, e.g., damper 220 depicted in FIG. 3 ), the respectiveattenuation strips typically have a pitch angle θ matching the windingangle θ_(w) of the core material (e.g., the paper strips that form ahelically-wound, paper-tube core). The spacing between adjacentattenuation strips is thus limited by manufacturing constraints (e.g.,winding angles). Increasing the number of attenuation-strip starts(e.g., three-start at a 120-degree offset or four-start at a 90-degreeoffset) might seem to facilitate more attenuation-strip contact betweenthe driveshaft damper and the inner surface of a propshaft. Driveshaftdampers with two or more attenuation strips are prone to delamination ifpoorly designed (e.g., attempting to bond a narrow attenuation strip toa seam gap on a helically-wound paperboard core). Moreover, if adjacentattenuation strips are placed too close, “hold-down” plies cannot bepositioned by conventional helical-winding machines between adjacentattenuation strips. As noted, without the “hold-down” plies mechanicallysecuring the attenuation strips to the core, the driveshaft damper maybe susceptible to delamination failure.

In another embodiment, the overlapping material may include polyetherfoam or other damping material (e.g., a polymeric batting or a polymericnonwoven, such as a 0.25-inch tufted polyester nonwoven). For example,additional overlapping material (e.g., foam, batting, or single-facecorrugated paper) can be positioned upon a “hold-down” ply or used inlieu of a “hold-down” ply.

In some embodiments, additional attenuation strips may be added withinthe limited space available between seam gaps. For example, multi-plycores typically exhibit seam gap joints (e.g., near butt gap joints thatyield gap joints) characterized by a narrow space between adjacentlateral edges of core material and an adjoining ply. FIG. 4 is anisolated, cut-away view of a portion of a representative helically-woundcore, which, for ease of understanding, is described herein as the core222 of the damper 220 of FIG. 3 . In the example depicted in FIG. 4 ,the core 222 includes seam gap joints, including wider, internal seamgap joints 236 and narrower, external seam gap joints 238. Referring toFIGS. 3 and 4 , in some embodiments, one or more attenuation strips 224,225 wind helically around the core 222 approximately adjacent to andnearly abutting the external seam gap joint 238 with consecutive helicalwindings around the core. For example, a driveshaft damper 220 mayinclude both a first attenuation strip 224 with a plurality of elongateprotrusions 226 and a second attenuation strip 225 with a plurality ofelongate protrusions 226. With consecutive helical windings around thecore 222, the first attenuation strip 224 helically-winds with its leftlateral edge approximately adjacent to and nearly abutting the externalseam gap joint 238 and the second attenuation strip 225 helically-windswith its right lateral edge approximately adjacent to and nearlyabutting the external seam gap joint 238. This might be facilitatedusing two attenuation strips of different widths.

Such seam gap joints 236, 238 are typically observable on the respectivesurface of the core 222 by an uneven surface and/or by exposed coreadhesive and/or underlying ply material. In some embodiments, it may bedifficult to adhere an attenuation strip 224, 225 overlapping anexternal seam gap 238 because of an uneven surface. Additionally,attenuation strips 224, 225 or adhesives used to adhere attenuationstrips to the core 222 may be incompatible with adhesives used tolaminate the plies of core material. As explained previously, theinitial, inner plies of core-material strips (i.e., the inner plies) arenarrower than the final, outer plies of core-material strips (i.e., theouter plies) to control seam-gap widening during core construction.

There is a need in the marketplace for driveshaft dampers providing morecontact surface (e.g., an increase in the number of contact surfacesengaging the inner surface of the driveshaft). Various embodiments ofthe present disclosure address this need. Some of these exemplaryembodiments may be characterized by attenuation strips having elongateprotrusions that together yield an effective pitch angle beingsignificantly greater than the winding angle of the core material and/orsignificantly greater than the winding angle typically feasible withconventional winding machines. Additional embodiments may becharacterized by attenuation strips that exhibit an effective pitchlength much greater than the pitch length typically feasible withconventional winding machines.

Without being bound to any theory, it is thought that this marketplaceneed can be addressed, overcoming the typical limitations ofconventional helical-winding machines, by providing driveshaft dampersthat have novel attenuation strips with a plurality of elongateprotrusions. The plurality of elongate protrusions advantageouslydecouples effective pitch length L_(e) from the winding angle θ_(w) ofthe core material. This allows the contact points for the attenuationstrips (e.g., the configuration and effective pitch length of theelongate protrusions) to be selected to provide improved damping andattenuation properties, while maintaining the width and other propertiesof the plies of core material within a range sufficient to meetstructural integrity or dimensional requirements for the core and/orlimitations associated with conventional continuous helical-windingprocesses. In some embodiments, the desired improvements in damping andattenuation properties associated with increasing the number of contactpoints may not be feasible in view of considerations associated withconventional helical-winding machines and structural integrity ordimensional requirements for the core, without decoupling effectivepitch length L_(e) from the winding angle θ_(w) of the core material asdisclosed herein. Various embodiments addressing this need may becharacterized by an effective pitch angle θ_(e), an effective pitchlength L_(e), and/or an effective pitch ratio P_(e) as discussed herein.

By way of example, FIG. 5 depicts an exemplary driveshaft damper 320configured in accordance with various embodiments of the presentdisclosure to provide an increase in the number of contact surfacesengaging the inner surface of a driveshaft (see, e.g., driveshaft 10 ofFIG. 1 ). The driveshaft damper 320 depicted in FIG. 5 includes a core322 formed of multiple plies of a helically-wound core materiallaminated with an adhesive, and two attenuation strips 324, 325 windinghelically about the circumference of the core (i.e., a two-startconfiguration). In some embodiments, helically-wound driveshaft damperswith more than two attenuation strips may be provided.

As depicted in FIG. 5 , the core has a diameter D, and two attenuationstrips 324, 325 helically wound around the circumference of the core atthe pitch angle θ. Embodiments with one attenuation strip or with morethan two attenuation strips are also within the spirit and scope of thepresent disclosure. The helical winding of the attenuation strips 324,325 exhibits a pitch length L, which may be measured longitudinally fromany selected position of each of the attenuation strips. Each of theattenuation strips 324, 325 has a plurality of elongate protrusions,such as a first elongate protrusion 326A, a second elongate protrusion326B, and a third elongate protrusion 326C. The attenuation strips 324,325 may be helically-wound at a pitch angle θ that provides adjacent andnearly abutting lateral edges of the attenuation strips 324, 325, sothat a narrow gap G may be provided between the adjacent lateral edgesof the attenuation strips 324, 325. Alternatively, in some embodiments,an attenuation strip or attenuation strips 324, 325 may be of a selectedwidth and/or helically wound at a selected pitch angle to provide arelatively wider gap G (not shown) between adjacent lateral edges. In anexemplary embodiment, the driveshaft damper 320 of FIG. 5 may have acore 322 with an outside diameter of 3.02 inches and a pitch length L of3.25 inches, which corresponds to a pitch angle θ of about 71 degrees.

As background for easing understanding of effective pitch angle θ_(e),FIG. 6 schematically depicts a 360-degree portion of a helical windingincluding two abutting, helically-wound strips and a diameter D, andFIG. 7 schematically depicts the helical winding portion of FIG. 6 in anunwound, flat configuration. In FIGS. 6 and 7 , cross-hatching isincluded to help distinguish the two strips from one another. FIGS. 6and 7 schematically depict that the helical winding portion generallyexhibits a pitch length L and an effective pitch Length L_(e). FIG. 7schematically depicts that the helical winding portion generallyexhibits a pitch angle θ and an effective pitch angle θ_(e). Theeffective pitch angle θ_(e) has a tangent equal to the ratio of thecircumference of the core over the effective pitch length L_(e).

An effective pitch angle θ_(e) can be calculated according to thisequation:

$\begin{matrix}{\theta_{e} = {{\arctan\left( \frac{\pi D}{L_{e}} \right)}.}} & \left( {{eq}.6} \right)\end{matrix}$Equation (6) shows that the effective pitch angle θ_(e) increases as theeffective pitch length L_(e) decreases. Together, eq. 1, eq. 5, and eq.6 indicate the tangent of the effective pitch angle θ_(e) equals thetangent of the pitch angle multiplied by the total number of elongateprotrusions on the surface of the driveshaft damper (i.e.,tan(θ_(e))=tan(θ)×total protrusions). In this regard and with reference,for example to the dampers 20, 120, 220, 320 of FIGS. 1-3 and 5 , theeffective pitch length L_(e) decreases as the number of elongateprotrusions increases. Accordingly, effective pitch angle θ_(e)increases as the number of elongate protrusions increases and decreasesas the number of elongate protrusions decreases.

A dimensionless effective pitch ratio may be calculated according tothis equation:

$\begin{matrix}{P_{e} = {\frac{{core}{diameter}}{{effective}{pitch}{length}}.}} & \left( {{eq}.7} \right)\end{matrix}$Equation (7) similarly shows that the effective pitch ratio increases asthe effective pitch length L_(e) decreases. Effective pitch ratio P_(e)also increases as the number of elongate protrusions increases, but incontrast with effective pitch angle θ_(e), effective pitch ratio P_(e)increases without asymptotic limitation (i.e., 90 degrees) as theeffective pitch length L_(e) becomes increasingly smaller.

As noted, only elongate protrusions configured to provide significantinterference fit within a driveshaft or a propshaft (e.g., at least 10percent elongate-protrusion displacement) ought to be considered indetermining effective pitch length L_(e) and its derivatives, effectivepitch angle θ_(e) and effective pitch ratio P_(e).

The pitch angle θ of driveshaft dampers made using a conventionalhelical-winding process may have a limited operating range in view ofconsiderations and limitations discussed herein. Typically, theoperating range for pitch angle θ of conventional helical-windingmachines falls between about 45 and 78 degrees (e.g., providing windingangles θ_(w) between 45 and 78, typically between 58 and 74 degrees,such as 58°, 59°, 60°, 61°, 62°, 63°, 64°, 65°, 66°, 67°, 68°, 69°, 70°,71°, 72°, 73°, 74°, etc.). For example, in some embodiments, thedriveshaft dampers 120, 220 in FIGS. 2 and 3 may have a core with anoutside diameter D of 3 inches and a pitch length L of about 3.24 inches(e.g., using 3 1/16-inch paper as the outer ply), which using equation(1) corresponds to a pitch angle θ of about 71 degrees.

When using attenuation strips with a single elongate protrusion,effective pitch angle θ_(e) and effective pitch ratio P_(e) aresimilarly limited. Driveshaft dampers made using a conventionalhelical-winding process may exhibit an effective pitch angle of betweenabout 45 and 78 degrees (e.g., between about 60 and 74 degrees). In acomparative driveshaft damper (e.g., 3-inch OD and a pitch angle θ ofabout 71 degrees), two attenuation strips each with one elongateprotrusion (i.e., two “single-ridge” attenuation strips) may beinstalled on a core. Using equation (5), a two-start “single-ridge”driveshaft damper may exhibit an effective pitch length L_(e) of about1.6 inches (i.e., 3.24-inch pitch length÷two elongate protrusions).Accordingly, equation (6) shows that a two-start “single-ridge”driveshaft damper might have an effective pitch angle θ_(e) of about 80degrees, and equation (7) indicates an effective pitch ratio of 1.85.

Conversely, the present disclosure provides for driveshaft dampersconfigured with attenuation strips that have two or more elongateprotrusions. For example, attenuation strips may each be provided withtwo, three, four, five, six, seven, eight, nine, ten or more, or perhapstwenty or more elongate protrusions. These additional elongateprotrusions allow the effective pitch angle θ_(e) to asymptoticallyapproach 90 degrees. For example, with an outside diameter D of 3 inchesand a pitch length L of 3.25 inches, the two-start driveshaft damper 320of FIG. 5 may exhibit an effective pitch length L_(e) of about 0.58 inch(i.e., a 3.25-inch pitch length÷six elongate protrusions) and aneffective pitch angle θ_(e) of about 86.5 degrees. As further examples,if two attenuation strips with five elongate protrusions each were usedin the driveshaft damper of FIG. 5 , this would yield an effective pitchangle θ_(e) of about 88 degrees (i.e., a 3.25-inch pitch length÷tenelongate protrusions). Similarly, two attenuation strips with tenelongate protrusions each would provide an effective pitch angle θ_(e)of about 89 degrees (i.e., a 3.25-inch pitch length÷twenty elongateprotrusions).

A desired effective pitch angle may be provided using any number ofelongate protrusions. For example, if one attenuation strip that has tenelongate protrusions were provided in a driveshaft damper similar to theexample in FIG. 5 , such a driveshaft damper would exhibit an effectivepitch length L_(e) of about 0.35 inch (i.e., a 3.25-inch pitchlength÷ten elongate protrusions) and an effective pitch angle θ_(e) ofabout 88 degrees. As another example, if such a driveshaft damper wereto include two attenuation strips, each with five elongate protrusions,this would provide a similar effective pitch length L_(e) of about 0.35inch (i.e., a 3.25-inch pitch length÷ten elongate protrusions) andeffective pitch angle θ_(e) of about 88 degrees. Even furtherembodiments are within the spirit and scope of the present disclosure.

Effective pitch ratio P_(e) may similarly be limited when using atypical helical-winding process. A single attenuation strip with oneelongate protrusion may have a pitch ratio P between 0.7 and 1.0 asdiscussed previously. Equation (7) shows that a comparative two-start“single-ridge” driveshaft damper (i.e., two “single-ridge” attenuationstrips) may have an effective pitch P_(e) ratio of about 1.8 or 1.9(e.g., a 3-inch diameter D÷an effective pitch length L_(e) of about 1.6inches). By contrast, the present disclosure provides for driveshaftdampers configured with attenuation strips that have more “contacting”elongate protrusions, which yield far greater increases to the effectivepitch ratio.

In various embodiments, a driveshaft damper with a plurality of elongateprotrusions may exhibit an effective pitch ratio P_(e) of at least 2.0(e.g., at least 2.1, 2.2, 2.3, 2.4, 2.5, 2.6, 2.7, 2.8, 2.9, etc.), atleast 3.0 (e.g., at least 3.1, 3.2, 3.3, 3.4, 3.5, etc.), at least 4.0(e.g., at least 4.1, 4.2, 4.3, 4.4, 4.5, etc.), at least 5.0 (e.g., atleast 5.1, 5.2, 5.3, 5.4, 5.5, etc.), at least 6.0 (e.g., at least 7.0,8.0, 9.0, etc.), at least 10 (e.g., at least 11, 12, 13, etc.), at least20, or even more. For example, the driveshaft damper 320 of FIG. 5 ,having an outside diameter D of 3.02 inches and a pitch length L of 3.24inches, may exhibit an effective pitch ratio P_(e) of about 5.6. Asanother example, if the two attenuation strips of the driveshaft damperof FIG. 5 have five elongate protrusions each, this would provide aneffective pitch ratio P_(e) of about 9.3. Further, if such attenuationstrips have ten elongate protrusions each, this would provide aneffective pitch ratio P_(e) of about 18.7. Moreover, attenuation stripswith twenty elongate protrusions each would provide an effective pitchratio P_(e) of about 37.3.

In some embodiments, a driveshaft damper may be provided withattenuation strips that have a plurality of elongate protrusionsexhibiting an effective pitch angle θ_(e) that exceeds the pitch angle θor winding angle θ_(w) of the core by a certain number of degrees. Forexample, the effective pitch angle θ_(e) may exceed the pitch angle θ orwinding angle θ_(w) of the core by 6° (e.g., 6.1°, 6.2°, 6.3°, 6.4,etc.), 7° (e.g., 7.1°, 7.2°, 7.3°, 7.4, etc.), 8° (e.g., 8.1°, 8.2°,8.3°, 8.4°, etc.), 9°, 10° or more (e.g., 10°, 11°, 12°, 13°, 14°), 15°or more (e.g., 15°, 16°, etc.), or even 20° or more (e.g., 25° or more).

In accordance with the present disclosure, driveshaft dampers can bemanufactured having effective pitch angles and effective pitch ratiosthat were previously unachievable via continuous helical-windingprocesses using conventional helical-winding machines (e.g., at windingangles between 45° and 80°). For example, Table 1 (below) providesexemplary effective pitch angles and effective pitch ratios achievableusing attenuation strips according to the present disclosure (e.g., oneor more attenuation strips having a total of three, four, or sixelongate protrusions configured for significant interference fit (e.g.,substantial frictional fit) within a driveshaft or propshaft.

TABLE 1 “interference” winding angle effective pitch angle effectivepitch ratio elongate protrusions θ_(w) (º) θ_(e) (°) θ_(e-)θ_(w) (P_(e))3 45 71.6 26.6 0.95 4 45 76.0 31.0 1.27 6 45 80.5 35.5 1.91 3 54 76.422.4 1.31 4 54 79.7 25.7 1.75 6 54 83.1 29.1 2.63 3 60 79.1 19.1 1.65 460 81.8 21.8 2.21 6 60 84.5 24.5 3.31 3 62 79.9 18.0 1.80 4 62 82.4 20.42.39 6 62 84.9 22.9 3.59 3 65 81.2 16.2 2.05 4 65 83.3 18.3 2.73 6 6585.6 20.6 4.10 3 68 82.3 14.3 2.36 4 68 84.2 16.2 3.15 6 68 86.1 18.14.73 3 70 83.1 13.1 2.62 4 70 84.8 14.8 3.50 6 70 86.5 16.5 5.25 3 7283.8 11.8 2.94 4 72 85.4 13.4 3.92 6 72 86.9 14.9 5.88 3 74 84.5 10.53.33 4 74 85.9 11.9 4.44 6 74 87.3 13.3 6.66 3 75 84.9 9.9 3.56 4 7586.2 11.2 4.75 6 75 87.4 12.4 7.13 3 76 85.2 9.2 3.83 4 76 86.4 10.45.11 6 76 87.6 11.6 7.66 3 77 85.6 8.6 4.14 4 77 86.7 9.7 5.52 6 77 87.810.8 8.27 3 78 85.9 7.9 4.49 4 78 87.0 9.0 5.99 6 78 88.0 10.0 8.98

In some exemplary embodiments, a driveshaft damper may include at leasttwo different kinds of attenuation strips having the same pitch angle θbut, measured individually, different effective pitch angles θ_(e). Asone example, a first attenuation strip might include only one elongateprotrusion (e.g., a “single-ridge” attenuation strip), and a secondattenuation strip might include two or more elongate protrusions (e.g.,a “triple-ridge” attenuation strip). As another example, a firstattenuation strip might include multiple elongate protrusions (e.g., a“triple-ridge” attenuation strip) and a second attenuation strip mightinclude a different number of elongate protrusions (e.g., two, four,five, or six elongate protrusions, etc.). As noted, attenuation stripsare typically positioned on a driveshaft damper at the same pitch angleθ to match the winding angle of the core material (e.g., the paperstrips that form a helically-wound, paper-tube core). In any suchembodiments using two or more different kinds of attenuation strips, theattenuation strips may be formed of the same kind of material havingdifferent durometers (e.g., a 50-durometer attenuation strip and a70-durometer attenuation strip) or different materials (e.g., EPDMrubber and heat-resistant silicone rubber) having similar or differentdurometers.

In addition to the exemplary embodiments discussed (above), attenuationstrips may be configured in various different ways, all of which arewithin the spirit and scope of the present disclosure. For example,additional exemplary attenuation strips are discussed (below).

FIGS. 8 and 9 each depict examples of continuous helical-windingprocesses in which multiple plies of core material and one or moreattenuation strips are wound concurrently around a mandrel. As depictedin FIG. 8 , the two-start driveshaft damper 220 of FIG. 3 may be formedusing a continuous helical-winding process. One or more plies of corematerial 240 (e.g., strips of paper, paperboard, or other core material)followed by one or more attenuation strips 224, 225 are helically woundaround a mandrel 242. As shown, a first “double-ridge” attenuation strip224 and a second “double-ridge” attenuation strip 225 are provided. Theattenuation strips 224, 225 are configured and arranged to avoidoverlapping a seam gap joint 38.

In another embodiment, FIG. 9 depicts the driveshaft damper 20 of FIG. 1formed using a similar continuous helical-winding process thatadvantageously overcomes the aforementioned limitations. As depicted inFIG. 9 , one or more plies of core material 40 followed by a“triple-ridge” attenuation strip 24 are helically wound around a mandrel42. The attenuation strip 24 may similarly be configured and arranged toavoid overlapping a seam gap joint 38. In some embodiments, however, awider attenuation strip may be permitted to overlap a seam gap joint 38if the added surface area of the attenuation strip's base facilitatessufficient bonding to the core material (i.e., without the seam gapjoint unsuitably interfering with adhesion by way of an uneven surfaceand/or incompatibility with core adhesive and/or underlying plymaterial).

A driveshaft damper also may be formed using a two-step process,including helically winding a core from a desired core material and thenhelically winding one or more attenuation strips around thealready-formed core. With a two-step process, various embodiments ofdriveshaft dampers may be produced in accordance with the presentdisclosure to achieve differing winding angle and pitch angles for thecore material and the attenuation strips, respectively. Typically,however, it is advantageous to produce driveshaft dampers using aone-step process configured to helically wind the plies of core materialand the one or more attenuation strips concurrently. Such a continuoushelical-winding process may yield a greater production efficiency ascompared with a two-step process, such as a faster production time and alower cost of production

FIGS. 10-12 depict exemplary helical-winding machines that may be usedto make helically-wound driveshaft dampers of this disclosure.

FIG. 10 is a top plan view of a winding machine 444. The winding machinesupplies a driving force configured both to wind (as indicated byhelical arrow 446) core material 440 around a mandrel 442 and to advancethe resulting core 422 longitudinally along the mandrel. As shown, thedriving force may be supplied by a pair of rollers 448 and a serpentinebelt 450. One or both rollers 448 may be driven by a suitable motor (notshown). The mandrel 442 typically remains stationary. The helical arrow446 indicates the direction of winding for the core material and otherarrows indicate the direction of rotation of the rollers 448 and thedirection of travel of the serpentine belt 450. The serpentine belt 450follows a path around a first roller 448, then around the mandrel 442and winding core material 440 at a nip point, then around a secondroller 448, turning over and then returning to the first roller 448. Forsimplicity, one ply of core material 440 is shown. It is to beunderstood, however, that such a process may be used for any number ofplies of core material 440.

FIG. 11 is a perspective view of another winding machine 544 that may beused to make a helically-wound driveshaft damper. This winding machine544 may be configured and arranged similarly to the winding machinedepicted in FIG. 10 . As depicted in FIG. 11 , a plurality of plies ofcore material 540 are provided and supported by respective hangers 552of a feeding assembly, so that first, second, and third plies of corematerial 540 are respectively supported by first, second, and thirdhangers 552. The winding machine 544 supplies a driving force configuredboth to wind core material 540 around a mandrel 542 and to advance theresulting core longitudinally along the mandrel. As shown, the drivingforce may be supplied by a pair of rollers 548 and a serpentine belt550. As explained with respect to FIG. 10 , one or both rollers 548 maybe driven by a suitable motor (not shown), and the mandrel 542 typicallyremains stationary.

FIG. 12 depicts another winding machine 644 that may be used to make ahelically-wound driveshaft damper. This winding machine 644 isconfigurable similarly to the winding machine in FIG. 11 . As depictedin FIG. 12 , five plies of core material 640 are respectively supportedby hangers 652 of a feeding assembly. The winding machine 644 supplies adriving force configured both to wind core material 640 around themandrel and to advance the resulting core longitudinally along themandrel. As shown, the driving force may be supplied by a pair ofrollers 648 and a serpentine belt 650. The winding machine 644 istypically configured so that one or both of the rollers 648 may bedriven by a suitable motor (not shown), and the mandrel typicallyremains stationary.

As noted, when employing a continuous helical-winding process usingconventional helical-winding machines, the winding angle θ_(w) needs tofall within a range that will facilitate both proper helical winding ofthe core material around the mandrel and advancement of the resultingcore along the mandrel. Stated otherwise, winding angle θ_(w) is limitedby factors associated with both manufacturing conditions and structuralrequirements of the core. The winding-angle θ_(w) operating range forconventional helical-winding machines falls between about 45 and 78degrees, and so the resulting helically-wound core typically exhibits acorresponding pitch angle θ of about 45 to 78 degrees (e.g., typicallyless than about 74 degrees to ensure good manufacturing runnability andproductivity). Concurrently forming a core (e.g., using paper strips)and mounting of an attenuation strip requires substantially the samepitch angle. For example, the winding angle θ_(w) of paper strips thatform a helically-wound, paper-tube core and the pitch angle θ of themounted attenuation strips are substantially the same (e.g., within 2degrees or so, such as within 1 degree or less) to ensure thehelical-winding machine yields satisfactory driveshaft-damper quality(e.g., the attenuation strips and the core material are helically woundat the same pitch angle). Maintaining the same pitch angle helps preventattenuation strips from overlapping either one another or a seam gap atthe core's surface. Overlapping is undesirable, because it can cause anuneven surface that compromises the adhesion of attenuation strips tothe core, and/or interferes with proper fit of the driveshaft damperinside a propshaft.

While one, three, and five plies of core material 440, 540, 640 arerespectively depicted in FIGS. 10-12 , it is to be understood thesenumbers of plies are shown for convenience only and that any suitablenumber of plies of core material (e.g., strips of paper, paperboard, orother core materials) may be provided. Those having ordinary skill inthe art will appreciate that the initial ply, which may be narrower,will typically form a seam gap so that the last ply, which may be wider,does not overlap upon itself during the formation of thehelically-wound, paper-tube core (i.e., the diameter of the paper-tubecore increases during the winding process). This also provides for amanufacturing tolerance to accommodate variation in the paper strips(e.g., +/−0.25-inch variance in a representative 4.5-inch paper strip)and the corresponding changes to pitch length. As noted, if the plywidth remains constant, the seam gap will widen as the diameter of theresulting core increases with successive plies of core material, and soto offset seam-gap widening during core construction, the inner plies ofcore-material strips are typically narrower than the outer plies ofcore-material strips.

In the embodiments depicted in FIGS. 10-12 , the one or more attenuationstrips are omitted for simplicity. As depicted in FIGS. 8 and 9 ,however, the one or more attenuation strips may be introduced at anysuitable point along the mandrel and concurrently wound around theresulting core.

Summarizing an exemplary method for forming a helically-wound driveshaftdamper, the method includes helically winding one or more plies of corematerial around a mandrel and, concurrently, helically winding one ormore attenuation strips around the resulting core. In the exemplarymethod, a driving force may be provided to helically wind the plies ofcore material. In the exemplary method, at least some of the drivingforce is transferred to the helically-wound plies of core material,advancing the core material longitudinally along the mandrel. In theexemplary method, the plies of core material may be laminated using anadhesive to form a core. In the exemplary method, the one or moreattenuation strips are bonded or otherwise secured to the core using anadhesive in a manner that ensures durability during driveshaftmanufacture and subsequent use, and such mounted attenuation stripsadvance longitudinally along the mandrel together with the core. Theattenuation strips may have one or more elongate protrusions, flanges,or other protuberant features. The one or more attenuation strips may beintroduced at any suitable location along the mandrel and/or windingcore. In some embodiments, the one or more attenuation strips may beintroduced after the resulting core is formed, winding concurrently withthe advancing core. Alternatively, one or more attenuation strips may beintroduced concurrently with the plies of core material, for example, inadvance of a serpentine belt or other driving force appropriatelyconfigured to interface with the one or more attenuation strips.

In one exemplary process embodiment, the method of making a driveshaftdamper includes helically winding plies of core material around amandrel at a winding angle θ_(w) to form a core, and concurrentlyhelically winding one or more attenuation strips (e.g., a “triple-ridge”attenuation strip) around the core as the core advances longitudinallyalong the mandrel and securing the one or more attenuation strips to thecore at a pitch angle θ. In one particular method embodiment, theconcurrent helical windings achieve (i) an effective pitch angle θ_(e)that exceeds both the winding angle θ_(w) and the pitch angle θ by atleast 10 degrees (e.g., at least 11 degrees, such as 12 degrees or more)and (ii) an effective pitch ratio P_(e) of at least 1.75 (e.g., at least1.8 or 1.9, such as 2.0 or more). In another particular methodembodiment, the concurrent helical windings achieve (i) an effectivepitch angle θ_(e) that exceeds both the winding angle θ_(w) and thepitch angle θ by at least 6.5 degrees (e.g., at least 7 or 8 degrees,such as 10 degrees or more) and (ii) an effective pitch ratio P_(e) ofat least 3.0 (e.g., at least 3.5, such as at least 4.0). In yet anotherparticular method embodiment, the concurrent helical windings achieve(i) an effective pitch angle θ_(e) that exceeds both the winding angleθ_(w) and the pitch angle θ by at least 16 degrees (e.g., at least 18 or20 degrees, such as 24 degrees or more) and (ii) an effective pitchratio P_(e) of at least 0.9 (e.g., at least 0.95, 1.0, 1.1, or 1.2, suchas at least 1.3 or 1.5). In yet another particular method embodiment,the concurrent helical windings achieve (i) an effective pitch angleθ_(e) that exceeds both the winding angle θ_(w) and the pitch angle θ byat least 7 degrees (e.g., at least 7.5 or 8 degrees, such as 9 degreesor more) and (ii) an effective pitch ratio P_(e) of at least 2.6 (e.g.,at least 2.75 or 2.9, such as at least 3.25 or 3.5). In yet anotherparticular method embodiment, the concurrent helical windings achieve(i) an effective pitch angle θ_(e) that exceeds both the winding angleθ_(w) and the pitch angle θ by at least 12 degrees (e.g., at least 13 or14 degrees, such as 16 degrees or more) and (ii) an effective pitchratio P_(e) of at least 1.5 (e.g., at least 1.8 or 2.0, such as at least2.3). In yet another particular method embodiment, the concurrenthelical windings achieve (i) an effective pitch angle θ_(e) that exceedsboth the winding angle θ_(w) and the pitch angle θ by at least 13degrees (e.g., at least 14 or 17 degrees) and (ii) an effective pitchratio P_(e) of at least 1.3 (e.g., at least 1.6, such as at least 2.1).In yet another particular method embodiment, the concurrent helicalwindings achieve (i) an effective pitch angle θ_(e) that exceeds boththe winding angle θ_(w) and the pitch angle θ by at least 14 degrees(e.g., at least 15 or 18 degrees, such as 20 degrees or more) and (ii)an effective pitch ratio P_(e) of at least 1.2 (e.g., at least 1.4, suchas at least 1.9). These parameters may be achieved, for example, byhelically winding an attenuation strip having at least three elongateprotrusions of the same height (e.g., substantially uniform dimensions)or by winding two or more attenuation strips each having at least twoelongate protrusions of uniform height (e.g., substantially uniformdimensions).

In another exemplary process embodiment, the method of making adriveshaft damper includes helically winding plies of core materialaround a mandrel at a winding angle θ_(w) (e.g., less than 80 degrees,such as 74 degrees or less) to form a core, and concurrently helicallywinding one or more attenuation strips around the core as the coreadvances longitudinally along the mandrel and securing the one or moreattenuation strips to the core at a pitch angle θ (e.g., less than 80degrees, such as 74 degrees or less). In one particular methodembodiment, the concurrent helical windings achieve (i) an effectivepitch angle θ_(e) that exceeds both the winding angle θ_(w) and thepitch angle θ (e.g., each 78 degrees or less) by more than 6.0 degrees(e.g., 7 degrees or more) and (ii) an effective pitch ratio P_(e) of atleast 3.0 (e.g., 4 or more). In another particular method embodiment,the concurrent helical windings achieve (i) an effective pitch angleθ_(e) that exceeds both the winding angle θ_(w) and the pitch angle θ(e.g., each about 77 degrees or less) by at least 7 degrees (e.g., 8degrees or more) and (ii) an effective pitch ratio P_(e) of at least 3(e.g., 3.5 or more). In yet another particular method embodiment, theconcurrent helical windings achieve (i) an effective pitch angle θ_(e)that exceeds both the winding angle θ_(w) and the pitch angle θ (e.g.,each about 76 degrees or less) by at least 7 degrees (e.g., 9 degrees ormore) and (ii) an effective pitch ratio P_(e) of at least 2.75 (e.g.,3.25 or more). In yet another particular method embodiment, theconcurrent helical windings achieve (i) an effective pitch angle θ_(e)that exceeds both the winding angle θ_(w) and the pitch angle θ (e.g.,each about 75 degrees or less) by at least 8 degrees (e.g., 9 degrees ormore) and (ii) an effective pitch ratio P_(e) of at least 2.5 (e.g., 3or more). In yet another particular method embodiment, the concurrenthelical windings achieve (i) an effective pitch angle θ_(e) that exceedsboth the winding angle θ_(w) and the pitch angle θ (e.g., each about 74degrees or less) by at least 8 degrees (e.g., 10 degrees or more) and(ii) an effective pitch ratio P_(e) of at least 2.3 (e.g., 2.8 or more).In yet another particular method embodiment, the concurrent helicalwindings achieve (i) an effective pitch angle θ_(e) that exceeds boththe winding angle θ_(w) and the pitch angle θ (e.g., each about 72degrees or less) by at least 9 degrees (e.g., 11 degrees or more) and(ii) an effective pitch ratio P_(e) of at least 2.2 (e.g., 2.5 or more).In yet another particular method embodiment, the concurrent helicalwindings achieve (i) an effective pitch angle θ_(e) that exceeds boththe winding angle θ_(w) and the pitch angle θ (e.g., each about 70degrees or less) by at least 10 degrees (e.g., 12 degrees or more) and(ii) an effective pitch ratio P_(e) of at least 1.9 (e.g., 2.25 ormore). In yet another particular method embodiment, the concurrenthelical windings achieve (i) an effective pitch angle θ_(e) that exceedsboth the winding angle θ_(w) and the pitch angle θ (e.g., each about 68degrees or less) by at least 11 degrees (e.g., 13 degrees or more) and(ii) an effective pitch ratio P_(e) of at least 1.7 (e.g., 2.2 or more).In yet another particular method embodiment, the concurrent helicalwindings achieve (i) an effective pitch angle θ_(e) that exceeds boththe winding angle θ_(w) and the pitch angle θ (e.g., each about 65degrees or less) by at least 12 degrees (e.g., 14 degrees or more) and(ii) an effective pitch ratio P_(e) of at least 1.5 (e.g., 1.75 ormore). In yet another particular method embodiment, the concurrenthelical windings achieve (i) an effective pitch angle θ_(e) that exceedsboth the winding angle θ_(w) and the pitch angle θ (e.g., each about 62degrees or less) by at least 14 degrees (e.g., 16 degrees or more) and(ii) an effective pitch ratio P_(e) of at least 1.3 (e.g., 1.6 or more).In yet another particular method embodiment, the concurrent helicalwindings achieve (i) an effective pitch angle θ_(e) that exceeds boththe winding angle θ_(w) and the pitch angle θ (e.g., each about 60degrees or less) by at least 15 degrees (e.g., 18 degrees or more) and(ii) an effective pitch ratio P_(e) of at least 1.2 (e.g., 1.4 or more).In yet another particular method embodiment, the concurrent helicalwindings achieve (i) an effective pitch angle θ_(e) that exceeds boththe winding angle θ_(w) and the pitch angle θ (e.g., each about 54degrees or less) by at least 18 degrees (e.g., 21 degrees or more) and(ii) an effective pitch ratio P_(e) of at least 1.0 (e.g., 1.2 or more).In yet another particular method embodiment, the concurrent helicalwindings achieve (i) an effective pitch angle θ_(e) that exceeds boththe winding angle θ_(w) and the pitch angle θ (e.g., each about 45degrees) by at least 20 degrees (e.g., 25 degrees or more) and (ii) aneffective pitch ratio P_(e) of at least 0.9 (e.g., 1.25 or more).Typically, the winding angle and the pitch angle θ are substantially thesame (e.g., within 1 degree or less, such as 0.5 degree or less) toensure the helical-winding machine yields satisfactory driveshaft-damperquality.

Attenuation strips may be configured and arranged in different ways inaccordance with the present disclosure. In this regard, during theassembly process an attenuation strip may be under sufficient tension tostretch. For example, helically winding an EPDM rubber attenuation stripor a silicone rubber attenuation strip onto a paperboard core may causethe rubber attenuation strip to stretch less than about 20 percent(e.g., less than about 10 percent). Typically, the dimensions of thestretched attenuation strip will reduce proportionally.

FIGS. 13 and 14 depict a comparative “single-ridge” attenuation strip754 with one elongate protrusion 756. The elongate protrusion 756 isconfigured to provide a contact surface with the inside surface of adriveshaft. The comparative attenuation strip 754 also includes asubstantially flat base 758 having opposite, lengthwise adhesion flanges760 configured to assist with bonding the comparative attenuation stripto a core. Referring to FIG. 14 , the comparative attenuation strip 754has a relatively narrow base 758 with a width WB of about 0.820±0.035inch. The height HP of the single elongate protrusion 756 is 0.250±0.012inch as measured from the bottom of the base 758. The lower, widestportion of the elongate protrusion 756 has a width WP of 0.080±0.014inch.

FIGS. 15-18 respectively depict exemplary attenuation strips 824, 924that include a plurality of elongate protrusions 826, 926, each of whichis configured to provide a contact surface (e.g., an interference fit)with the inside surface of a driveshaft. As depicted in FIG. 15 andFIGS. 16A, 16B, and 16C, an exemplary “double-ridge” attenuation strip824 includes a first elongate protrusion 826 configured to provide afirst contact surface with the inside surface of a driveshaft and asecond elongate protrusion 826 configured to provide a second contactsurface with the inside surface of a driveshaft. As depicted in FIGS. 17and 18 , the exemplary “triple-ridge” attenuation strip 924 includes afirst elongate protrusion 926 configured to provide a first contactsurface with the inside surface of a driveshaft, a second elongateprotrusion 926 configured to provide a second contact surface with theinside surface of a driveshaft, and a third elongate protrusion 926configured to provide a third contact surface with the inside surface ofa driveshaft.

Both the exemplary “double-ridge” attenuation strip 824 and theexemplary “triple-ridge” attenuation strip 924 respectively includeadhesion flanges 830, 930 configured to assist with bonding eachexemplary attenuation strip to a core (e.g., each attenuation-stripembodiment 824, 924 respectively includes a substantially flat base 828,928 respectively having lengthwise adhesion flanges 830, 930 on oppositesides of the elongate protrusions). The attenuation strips 824, 924 maybe configured with any suitable dimensions, and with any suitable numberof elongate protrusions 826, 926, flanges 830, 930, or other protuberantfeatures. For example, an attenuation strip may have between two and ten(e.g., three, four, five six, etc.) or even more elongate protrusions(e.g., 20 or more protrusions) provided sufficient spacing is available.In exemplary embodiments, the attenuation strips (e.g., attenuationstrips 824, 924) may be formed of EPDM (e.g., 55+/−5 Shore A durometer)and/or silicone rubber (e.g., 24-44 Shore A durometer).

As examples, the double-ridge attenuation strip 824 of FIG. 15 and FIGS.16A, 16B, and 16C can be representative of the above-discussedattenuation strips 124 (FIG. 2 ), 224 (FIGS. 3 and 8 ), 225 (FIGS. 3 and8 ). Each of the attenuation strips 124, 224, 225 may be like theattenuation strip 824, except for variations noted and variations thatwill be apparent to those of ordinary skill in the art. Similarly, andas further examples, the exemplary triple-ridge attenuation strip 924depicted in FIGS. 17 and 18 can be representative of the above-discussedattenuation strips 24 (FIGS. 1 and 9 ), 324 (FIG. 5 ), 325 (FIG. 5 ).Each of the attenuation strips 24, 324, 325 may be like the attenuationstrip 924, except for variations noted and variations that will beapparent to those of ordinary skill in the art.

Each of the double-ridge attenuation strip 824 (FIG. 15 and FIGS. 16A,16B, and 16C) and the triple-ridge attenuation strip 924 (FIGS. 17 and18 ) can be incorporated into various differently configured driveshaftdampers. For example, FIG. 19 is a cross-sectional view of an exemplarydriveshaft damper 920 with the cross section taken perpendicular thelength of the damper. The driveshaft damper 920 has a core 922 and twoattenuation strips 924 helically wound around the core. The triple-ridgeattenuation strips 924 each have three elongate protrusions 926. Theattenuation strips 924 wind helically around the core 922 at a pitchangle that provides adjacent, spaced apart lateral edges of theattenuation strips, as indicated by relatively wide gaps G between thelateral edges (e.g., the adjacent adhesion flanges 930). Alternatively,a wider pitch angle may be selected to provide a somewhat narrower gapG.

Referring to FIGS. 16A, 16B, and 16C and FIG. 18 , in some embodiments,an attenuation strip with a plurality of elongate protrusions may have abase with a width WB ranging from 0.5 to 12 inches wide (e.g., 2.20inches or 2.44 inches wide for a “triple-ridge” attenuation strip). Theheight HP of each of the plurality of elongate protrusions may rangefrom 0.1 to 0.5 inch (e.g., 0.125 inch or 0.375 inch). As noted, theheight HP of each elongate protrusion is measured from the bottom of theattenuation strip's base to the peak of the elongate protrusion. Theelongate protrusions may have a width WP ranging from 0.05 to 0.25 inch(e.g., about 0.10 inch), and, in some embodiments, the elongateprotrusions may have a taper TP on one or both sides (e.g., betweenabout 1 and 10 degrees, such as about 3 to 8 degrees). The elongateprotrusions may be spaced SP laterally along the attenuation stripbetween 0.1 inch to 4 inches apart, measured center-to-center. Theelongate protrusions may be spaced equally from one another, or atvarying distances, as may be suitable for various applications. In someembodiments, an attenuation strip may have a flat-base thickness TBbetween about 0.025 and 0.25 inch between the elongate protrusions(i.e., toward the middle of the “triple-ridge” attenuation strip). Theadhesion flanges may have a width WF of between about 0.2 and 0.5 inch(e.g., 0.25 inch to 0.4 inch) and a thickness TF ranging from 0.01 to0.2 inch (e.g., an edge thickness of 0.02 inch to 0.15 inch). Inexemplary embodiments, an adhesion flange may have a taper on the topsurface extending from the adjacent elongate protrusion. The dimensionsand other characteristics of the attenuation strips, such as thethickness of the attenuation strips and the protrusion heights, may beadjusted to change the mass of the attenuation strip, for example totune the driveshaft damper (e.g., to effect broad-band tuning).

Referring to FIG. 16A, a first version of the double-ridge attenuationstrip 824 may have a maximum height (e.g., protrusion height HP) of0.250±0.012 inch and a width (e.g., base width WB) of 1.640±0.063inches. The maximum height (e.g., protrusion height HP) of the firstversion attenuation strip 824 is typically the vertical distance to thepeak of the tallest elongate protrusions from the lower surface of theattenuation strip's base. The first version attenuation strip 824 hastwo uniform elongate protrusions, which may be spaced 0.800 inch apartmeasured center-to-center. The elongate protrusions may have a width(e.g., protrusion width WP) of 0.080±0.014 inch at the protrusion basewith a taper TP of 5.0 degrees on each side extending from the base ofthe first version attenuation strip 824 (i.e., the upper surface of theattenuation-strip base). An exemplary ratio of the maximum height of theattenuation strip (e.g., at an elongate-protrusion peak) to the maximumwidth of the elongate protrusion is between 2 and 4 (e.g., between about2.5 and 3.5). The outer adhesion flanges 830 of the first versionattenuation strip 824 may have a width WF of about 0.38 inch and athickness TF of 0.030±0.010 inch at their respective ends, which reflecta taper of about 2 degrees on the top side of the adhesion flangeextending from the adjacent elongate protrusion. The first versionattenuation strip 824 may have a thickness (e.g., base thickness TB) of0.054±0.010 inch between the elongate protrusions (i.e., toward themiddle of the “double-ridge” first version attenuation strip 824),whereby the height of the elongate protrusions is between about 0.174inch and 0.218 inch (e.g., 0.196 inch) as measured from the uppersurface of the attenuation-strip base.

Referring to FIG. 16B, a second version of the double-ridge attenuationstrip 824 has a thicker base (e.g., about 1 millimeter thicker). Thisprovides more stiffness and mass to the driveshaft damper. The secondversion of the double-ridge attenuation strip 824 is otherwise similarto the thinner, first version of the double-ridge attenuation strip 824.The second version of the double-ridge attenuation strip 824 may have amaximum height (e.g., protrusion height HP) of 0.250±0.012 inch and awidth (e.g., base width WB) of 1.640±0.063 inches. As noted, the maximumheight of the attenuation strip is typically the vertical distance tothe peak of the tallest elongate protrusions from the lower surface ofthe attenuation strip's base. The two uniform elongate protrusions ofthe second version of the double-ridge attenuation strip 824 may bespaced 0.800 inch apart measured center-to-center. The elongateprotrusions of the second version of the double-ridge attenuation strip824 may have a width (e.g., protrusion width WP) of 0.080±0.014 inch atthe protrusion base with a taper TP of 6.0 degrees on each sideextending from the base of the attenuation strip (i.e., the uppersurface of the attenuation-strip base). The outer adhesion flanges 830of the second version of the double-ridge attenuation strip 824 may havea width WF of about 0.38 inch and an increased thickness TF of0.069±0.010 inch at their respective ends, which reflects a taper on thetop side of the adhesion flange extending from the adjacent elongateprotrusion. The second version of the double-ridge attenuation strip 824may have an increased thickness TB of 0.093±0.010 inch between theelongate protrusions (i.e., toward the middle of the “double-ridge”attenuation strip), whereby the height of the elongate protrusions isbetween about 0.179 inch and 0.135 inch (e.g., 0.157 inch) as measuredfrom the upper surface of the attenuation-strip base.

Referring to FIG. 16C, a third version of the double-ridge attenuationstrip 824 has an even thicker base (e.g., about 2 millimeters thicker).This provides even more stiffness and mass to the driveshaft damper. Thethird version of the double-ridge attenuation strip 824 is otherwisesimilar to the first and second versions of the double-ridge attenuationstrip 824. The third version of the double-ridge attenuation strip 824may have a maximum height (e.g., protrusion height HP) of 0.250±0.012inch and a width (e.g., base width WB) of 1.640±0.063 inches. As noted,the maximum height of the attenuation strip is typically the verticaldistance to the peak of the tallest elongate protrusions from the lowersurface of the attenuation strip's base. The two uniform elongateprotrusions of the third version of the double-ridge attenuation strip824 may be spaced 0.800 inch apart measured center-to-center. Theelongate protrusions of the third version of the double-ridgeattenuation strip 824 may have a width (e.g., protrusion width WP) of0.080±0.014 inch at the protrusion base with a taper TP of 6.3 degreeson each side extending from the base of the attenuation strip (i.e., theupper surface of the attenuation-strip base). The outer adhesion flanges830 may have a width WF of about 0.38 inch and an increased thickness TFof 0.108±0.010 inch at their respective ends, which reflects a taper onthe top side of the adhesion flange extending from the adjacent elongateprotrusion. The third version of the double-ridge attenuation strip 824may have an increased thickness TB of 0.132±0.010 inch between theelongate protrusions (i.e., toward the middle of the “double-ridge”attenuation strip), whereby the height of the elongate protrusions isbetween about 0.140 inch and 0.96 inch (e.g., 0.118 inch) as measuredfrom the upper surface of the attenuation-strip base.

Referring to FIGS. 17 and 18 , a first version of the triple-ridgeattenuation strip 924 may have a maximum height (e.g., protrusion heightHP) of 0.250±0.012 inch and a width (e.g., base width WB) of 2.440±0.063inches. The first version of the triple-ridge attenuation strip 924 hasthree uniform elongate protrusions, each of which may be spaced SP 0.800inch apart measured center-to-center. The elongate protrusions of thefirst version of the triple-ridge attenuation strip 924 may have a width(e.g., protrusion width WP) of 0.080±0.014 inch at the protrusion basewith a taper TP of 5.0 degrees on each side extending from the base ofthe attenuation strip (i.e., the upper surface of the attenuation-stripbase). The adhesion flanges 930 of the first version of the triple-ridgeattenuation strip 924 may have a width WF of about 0.38 inch and athickness TF of 0.030±0.010 inch at their outer ends, which reflect ataper of 2.0 degrees on the top side of the adhesion flange extendingfrom the adjacent elongate protrusion. The first version of thetriple-ridge attenuation strip 924 may have a base thickness TB of0.054±0.010 between the elongate protrusions (i.e., toward the middle ofthe “triple-ridge” attenuation strip), whereby the height the elongateprotrusions is between about 0.174 inch and 0.218 inch (e.g., 0.196inch) as measured from the upper surface of the attenuation-strip base.

Referring to FIGS. 17 and 18 , a second version of the triple-ridgeattenuation strip 924 may have a maximum height (e.g., protrusion heightHP) of 0.250±0.012 inch and a width (e.g., base width WB) of about 2.20inches. The second version of the triple-ridge attenuation strip 924 hasthree uniform elongate protrusions spaced 0.800 inch apart from theadjacent protrusion as measured center-to-center. The elongateprotrusions of the second version of the triple-ridge attenuation strip924 are between about 0.08 inch and 0.10 inch wide at the protrusionbase and include a taper TP of 5.0 degrees on each side extending fromthe base of the attenuation strip (i.e., the upper surface of theattenuation-strip base). The adhesion flanges of the second version ofthe triple-ridge attenuation strip 924 are about 0.25 inch wide andabout 0.030 inch thick at their outermost ends. Each adhesion flange ofthe second version of the triple-ridge attenuation strip 924 is slightlytapered (e.g., 2 degrees or so) at the top side of the attenuation-stripbase. The second version of the triple-ridge attenuation strip 924 mayhave a base thickness TB of 0.054±0.010 between the elongate protrusions(i.e., toward the middle of the “triple-ridge” attenuation strip),whereby the height of the elongate protrusions is between about 0.174inch and 0.218 inch (e.g., 0.196 inch) as measured from the uppersurface of the attenuation-strip base. U.S. Patent Application No.62/748,204 for Driveshaft Dampers and Systems and Methods for Making andUsing the Same (filed Oct. 19, 2018), which is incorporated by referencein its entirety, includes exemplary engineering specifications andmeasurements for these “triple-ridge” attenuation strips, as well asphotographs of a “triple-ridge” attenuation strip prototype.

Attenuation strips may be characterized by a dimensionlessbase-to-protrusion ratio (BPR) using this equation:

$\begin{matrix}{{BPR} = {\frac{{width}{of}{base}}{{maximum}{height}{of}{elongated}{protrusions}}.}} & \left( {{eq}.8} \right)\end{matrix}$Typical attenuation strips with a single elongate protrusion may exhibita base-to-protrusion ratio BPR ranging from 1 to 5. For example, theattenuation strip depicted in FIGS. 13 and 14 may have abase-to-protrusion ratio BPR of about 3.3 (i.e., 0.82-inch basewidth÷0.25-inch protrusion height).

By comparison, exemplary attenuation strips with a plurality of elongateprotrusions may exhibit a base-to-protrusion ratio BPR 1 to 100, orgreater. Exemplary attenuation strips with two or three elongateprotrusions have a BPR of greater than 5 (e.g., 6 to 12). For example,the “triple-ridge” attenuation strip depicted in FIGS. 17 and 18 has abase-to-protrusion ratio BPR between about 8 and 10 (e.g., 2.20-inch or2.44-inch base width÷0.25-inch protrusion height). In some embodiments,exemplary attenuation strips with a plurality of elongate protrusionsmay exhibit a base-to-protrusion BPR of at least 10, at least 15, atleast 20, at least 25, or at least 50 or more. Attenuation strips withmultiple elongate protrusions are typically designed so the protrusionsare uniform in at least height (e.g., dimensions within manufacturingtolerances of less than 5 percent variation, such as less than 3 percentvariation). If an attenuation strip has multiple elongate protrusions ofdiffering heights, the height of the tallest elongate protrusion asmeasured from the bottom of the attenuation strip's base shoulddetermine base-to-protrusion ratio (BPR).

Moreover, attenuation strips may be characterized by a dimensionlessprotrusion-spacing ratio (PSR) using this equation:

$\begin{matrix}{{PSR} = {\frac{{mean}{spacing}{between}{adjacent}{protrusions}}{{maximum}{height}{of}{elongated}{protrusions}}.}} & \left( {{eq}.9} \right)\end{matrix}$As noted, spacing between adjacent elongate protrusions is laterallymeasured center-to-center as illustrated in FIGS. 17 and 18 . Typicalattenuation strips with two or more elongate protrusions may exhibit aprotrusion-spacing ratio PSR ranging between 1 and 5, such as between 2and 4 (e.g., about 3). For example, the attenuation strip depicted inFIGS. 17 and 18 has a protrusion-spacing ratio PSR of about 3.2 (i.e.,0.80-inch mean protrusion spacing÷0.25-inch protrusion height). A4.25-inch attenuation strip having sixteen (16) 0.25-inch elongateprotrusions equally spaced at 0.25-inch increments would have aprotrusion-spacing ratio PSR of 1 (i.e., 0.25-inch mean protrusionspacing÷0.25-inch protrusion height). It is thought that, for a givennumber of protrusions on an attenuation strip, a protrusion-spacingratio PSR of at least 1 will provide better damping across thedriveshaft damper (i.e., the elongate protrusions are greater spacedfrom one another.) If an attenuation strip has multiple elongateprotrusions of differing heights, the height of the tallest elongateprotrusion as measured from the bottom of the attenuation strip's baseshould determine protrusion-spacing ratio (PSR).

As noted, attenuation strips with multiple elongate protrusions aretypically designed so the protrusions are uniform, because this achieveseffective NVH damping. Unless otherwise stated, the standardprotrusion-spacing ratio (PSR) is reported using all elongateprotrusions. Alternatively, the protrusion-spacing ratio (PSR) may becharacterized for an attenuation strip with multiple elongateprotrusions of differing heights by disregarding elongate protrusionsthat are significantly shorter than the tallest elongate protrusion. Inthis regard, protrusion-spacing ratio (PSR) may be determined bydisregarding elongate protrusions (e.g., outboard ribs) that are notconfigured for significant interference fit within a driveshaft or apropshaft. For example, protrusion-spacing ratio (PSR) may be calculatedby disregarding protrusions that are less than 70 percent (PSR₇₀), lessthan 80 percent (PSR₈₀), or even less than 90 percent (PSR₉₀) of thetallest elongate protrusion. In these alternative PSR calculations fornon-uniform elongate protrusions, the mean protrusion spacing mayincrease, and the reported alternative protrusion-spacing ratio (e.g.,(PSR₇₀, PSR₈₀, or PSR₉₀) may increase relative to standard PSR.

Both the base-to-protrusion ratio (BPR) and the protrusion-spacing ratio(PSR) are reported herein in a free state (i.e., unstretched). Thatsaid, the dimensions of a stretched attenuation strip should reduceproportionally during assembly, and so the base-to-protrusion ratio(BPR) and the protrusion-spacing ratio (PSR) ought to be consistent ineither a relaxed or a stretched state. Moreover, either thebase-to-protrusion ratio (BPR) or the protrusion-spacing ratio (PSR) maybe designed to modify the damping characteristics of the driveshaftdamper (e.g., to reduce or shift resonance frequencies) as installed ina particular propshaft.

In this regard, a tensioned attenuation strip might stretch during theassembly process. For example, helically winding an EPDM rubberattenuation strip or a silicone rubber attenuation strip onto apaperboard core may cause a rubber attenuation strip to stretch lessthan about 20 percent. Typically, the dimensions of the stretchedattenuation strip will reduce proportionally.

Additional examples of attenuation strips are depicted in FIGS. 20-25 ,wherein each is depicted in isolation in its flat configuration. Asdepicted in FIG. 20 , an attenuation strip 1024 may include several(e.g., eight) elongate protrusions 1026. The attenuation strip 1024 mayhave a suitable width WB of, for example, about 4 inches. For example,the elongate protrusions 1026 may be spaced from one another with aspacing SP of, for example, about 0.5 inch, and the attenuation strip1024 may have adhesion flanges 1030 that have a width WF of, forexample, about 0.25 inch.

As depicted in FIG. 21 , an attenuation strip 1124 may include several(e.g., five) elongate protrusions 1126. The attenuation strip 1124 mayhave a suitable width WB of, for example, about 4.5 inches. For example,the elongate protrusions 1126 may be spaced from one another with aspacing SP of, for example, about 1.0 inch, and the attenuation strip1124 may have adhesion flanges 1130 that have a width WF of, forexample, about 0.25 inch.

As depicted in FIG. 22 , an attenuation strip 1224 may include several(e.g., four) elongate protrusions 1226. The attenuation strip 1224 mayhave a suitable width WB of, for example, about 3 inches. For example,the elongate protrusions 1226 may be spaced from one another with aspacing SP of, for example, about 0.8 inch, and the attenuation strip1224 may have adhesion flanges 1230 that have a width WF of, forexample, about 0.3 inch.

FIGS. 23-25 depict additional exemplary attenuation strips. Attenuationstrips may be wound helically or convolutely around a core. As depictedin FIG. 23 , an attenuation strip 1324 may have elongate protrusions1326 oriented substantially parallel to the length of the attenuationstrip. With the attenuation strip 1324 helically wound around a core,the elongate protrusions 1326 typically follow a helical path around thecore. Alternatively, with the attenuation strip 1324 wound convolutelyaround the core, the elongate protrusions 1326 may follow a pathsubstantially parallel to the longitudinal axis of the driveshaftdamper.

As depicted in FIG. 24 , an attenuation strip 1424 may have elongateprotrusions 1426 oriented perpendicular to the length of the attenuationstrip. The perpendicular elongate protrusions 1426 may be configured sothat when helically wound around a core, various elongate protrusions(e.g., adjacent protrusions) substantially align with one another. Insome embodiments (e.g., an attenuation strip placed with abuttinglateral edges), substantially aligned elongate protrusions 1426 maycombine to form a contact surface that appears to wind around the core(e.g., helically at a complementary angle), at least for a portion ofthe length of the driveshaft damper. Alternatively, the perpendicularelongate protrusions 1426 may be configured to be staggered from oneanother when helically wound around the core. In yet another embodiment,with a convolute configuration of the attenuation strip 1424, theelongate protrusions 1426 may form concentric rings around the perimeterof the core.

As depicted in FIG. 25 , an attenuation strip 1524 may have elongateprotrusions 1526 oriented at an oblique angle with respect to the lengthof the attenuation strip. The oblique angle may be selected to obtain adesired configuration with the attenuation strip wound around the core.For example, the oblique angle of the elongate protrusions 1526 may beconfigured so that when helically wound around a core, various elongateprotrusions (e.g., adjacent protrusions) substantially align with oneanother. In some embodiments, opposite sides of an elongate protrusion1526 may substantially align with one another. In some embodiments,different elongate protrusions 1526 may substantially align with oneanother, for example, forming a helical path that differs from the pitchangle θ of the attenuation strip (e.g., the complement of pitch angleθ). Alternatively, substantially aligned elongate protrusions 1526 maycombine to form a contact surface that runs parallel to the longitudinalaxis of the driveshaft damper, at least for a portion of the length ofthe driveshaft damper. In yet another embodiment, with the attenuationstrip 1524 wound convolutely around the core, the elongate protrusions1526 may form a helical path around the perimeter of the core. Forexample, a lateral edge of one elongate protrusion 1526 maysubstantially align with a corresponding lateral edge of anotherelongate protrusion 1526 to form a helical path from a convolutelywrapped attenuation strip.

In some embodiments, a driveshaft damper may be configured to include,in addition to one or more attenuation strips, a second dampingmaterial, such as foam, textile acoustic insulation (e.g.,sound-absorbing textiles), or other damping material (e.g., a polymericbatting, such as polyester batting, a polymeric nonwoven, such as atufted polyester nonwoven, or single-face corrugated paper) configuredto engage or otherwise contact the inner surface of the driveshaft. Thesecond damping material may be positioned between attenuation strips orbetween protrusions of attenuation strips. The NVH-reducing attenuationstrips are typically secured to the exterior surface of the core orother substantially cylindrical structure (e.g., a substantiallycylindrical substrate tube). The foam or other second damping materialmay be secured to one or both surfaces of the substantially cylindricalcore (i.e., the interior surface and/or exterior surface).

For example, foam may be adhesively bonded or otherwise secured in ahelical strip to the outer surface of the substantially cylindrical core(e.g., a paperboard tube). Alternatively, foam can be extruded (e.g., asone of more beads) onto the outer surface of the substantiallycylindrical core in areas not already covered by an attenuation strip orbetween protrusions of the attenuation strips. As an example of anembodiment with foam mounted to the outer surface of the core, FIG. 29depicts a version of the driveshaft damper 20 (FIGS. 1, 9, 26, and 27 )that further includes a helically configured strip of foam 62 (e.g.,surficial foam, such as polyether foam) mounted (e.g., via adhesivematerial) to the outer surface of the core 22 (FIGS. 9, 26, and 27 ).FIGS. 30 and 31 depict the version of the driveshaft damper 20 includingthe foam strip 62 installed in a driveshaft 10.

Moreover, it is within the scope of the present disclosure to adhesivelybond or otherwise secure foam or other second damping material to theinner surface of the substantially cylindrical core, either with orwithout the presence of exterior, surficial foam or exterior, seconddamping material. In this regard, substantially the entire annular spaceformed by the core or other substantially cylindrical structure may befilled with foam or other second damping material. As an example of anembodiment with a second dampening material in the interior of the core,FIG. 32 depicts a version of the driveshaft damper 20 that includes asheet or strip of foam 63 (e.g., surficial foam, such as polyether foam)mounted to the inner surface of the core 22. FIG. 33 depicts anotherversion of the driveshaft damper 20 that includes a cylindrical plug offoam 64 (e.g., polyether foam) substantially filling the interior of thecore 22. The versions of the driveshaft damper 20 depicted in FIGS. 32and 33 may further include a helically configured hold-down ply 32mounted (e.g., via adhesive material) to the outer surface of the core22, and the helically configured strip of foam 62 (e.g., surficial foam,such as polyether foam) mounted (e.g., via adhesive material) to theouter surface of the core 22.

It is further within the scope of the present disclosure to tune thedriveshaft damper to provide improved NVH reduction by reducingproblematic NVH for a particular driveshaft as installed in a particularvehicle. For example, the second damping material's density, thickness,resilience, and durometer can be selected so as to dampen a particularlyproblematic resonance frequency (i.e., to provide a tuned driveshaftdamper). Likewise, the attenuation strip's density, thickness,resilience, durometer, and length can be selected so as to dampen aparticularly problematic resonance frequency. Similarly, the density,wall thickness, and length of the substantially cylindrical structure(e.g., a paperboard core or tube) can be selected so as to dampen aparticularly problematic resonance frequency.

In this regard, the driveshaft damper may employ second damping material(e.g., foam) in a constant or variable thickness. For example, thethickness of the second damping material might be varied along thesubstantially cylindrical core (e.g., the foam thickness is not constantby applying foam strips or beads of differing thickness) in order toselectively dampen multiple (i.e., more than one) NVH-causingfrequencies.

By way of non-limiting illustration, the second damping material (e.g.,foam or textile acoustic insulation) and the substantially cylindricalcore operate as a spring-mass system. Those having ordinary skill in theart will appreciate that a spring-mass system can be used to dampenvibration by moving the mass out of phase with the vibration source.

By way of further explanation, the second damping material may representthe spring, and the substantially cylindrical core (e.g., a paperboardcore) may represent the mass in this spring-mass system. Because thedensity of the second damping material and the wall thickness of thesubstantially cylindrical core can be varied to dampen specificresonance frequencies, the driveshaft damper may serve as a tuned massdamper (e.g., an active mass damper or harmonic absorber).

Those having ordinary skill in the art will recognize that, in any ofthese configurations, the second damping material (e.g., foam or textileacoustic insulation) will bond or otherwise adhere to the substantiallycylindrical core such that the second damping material will remain inplace while the driveshaft damper is placed inside a propshaft (e.g.,bonded to ensure durability during driveshaft manufacture and subsequentuse).

Exemplary foam may be an elastomeric foam, such as polyurethane and/orpolyether foam. For heat resistance, the foam may be formed of a foamedsilicone that has high-temperature resistance. A suitable silicone forforming heat-resistant foam is Dow Corning's 3-8186 Thixotropic Foam. Inthis regard and as noted, this application incorporates entirely byreference commonly assigned U.S. Pat. No. 8,801,526 and commonlyassigned U.S. Pat. No. 9,599,147.

Polyether foam (e.g., charcoal polyether foam) provides enhanced dampingcharacteristics. Alternative foam materials (e.g., for forming anopen-cell foam) include polyester foam, polyurethane foam, and siliconefoam. With respect to the present composite driveshaft dampers enhancedwith a second damping material, suitable foams (e.g., polyether foam)typically have (i) a density of between about 1.0 lb/ft³ and 3.5 lbs/ft³(e.g., between about 1.05 lbs/ft³ and 1.15 lbs/ft³), typically at leastabout 1.5 lbs/ft³ (e.g., between about 1.75 lbs/ft³ and 3.0 lbs/ft³),(ii) an indent-force deflection at 25 percent of between about 28 psiand 36 psi, (iii) a tensile strength of at least about 10 psi, (iv) atear strength of at least about 1.0 psi, and (v) a minimum elongation ofat least about 100 percent.

When installed on a substantially cylindrical core (e.g., a paper-tubecore), the foam typically has a thickness of between about 0.1 inch and2.0 inches (e.g., 0.25 inch to 0.5 inch). By way of illustration, asuitable cylindrical structure may be a paperboard tube having (i) alength of between about 8 inches and 52 inches (e.g., between about 8inches and 16 inches), (ii) a paper density of between about 3.3lbs/1000 ft² and 3.7 lbs/1000 ft², and (iii) a tube wall thickness ofbetween about 0.04 inch and 0.25 inch (e.g., 0.1 inch to 0.2 inch).

FIGS. 34-36 depict the damping mechanisms provided by an exemplarydriveshaft damper having NVH-reducing materials covering one or more ofits surfaces (e.g., the outer surface, or both the inner and outersurfaces). Exemplary driveshaft dampers according to the presentdisclosure are depicted in at least FIGS. 1-3, 5, 19, and 26-32 . Forexample, the combination of surficial foam (e.g., polyether foam) andsurficial non-foamed attenuation strip(s) (e.g., EPDM or silicone rubberretaining members) covering a cylindrical carrier structure (e.g., apaperboard tube) provides both active and passive dampening. See, e.g.,FIGS. 29-33 (depicting exemplary driveshaft dampers having asingle-start “triple-ridge” attenuation strip with surficial foam). Asdepicted in FIG. 34 , the driveshaft damper provides a spring-masssystem whose oscillations quickly decay (e.g., due to spring rate and/orhysteresis damping) after being deflected because of contact between avibrating driveshaft and the driveshaft damper. Although the surfacefoam (e.g., interior and/or exterior foam) and non-foamed attenuationstrip(s) (e.g., retaining members) transmit and absorb much of thevibrational energy, the cylindrical carrier structure also functions totransmit and absorb vibrational energy, as well as to provide mass forthe spring-mass system. The main spring rates or spring-force constantsof the spring-mass system are thought to be primarily a function of theconfigurations (e.g., compressive elasticity) of the elongateprotrusions of the driveshaft damper's one or more attenuation strips.With respect to damper tuning, the configuration of the one or moreattenuation strips (e.g., the compressive elasticity of the elongateprotrusions) can be selected and/or adjusted to change the spring ratesor force constants of the spring-mass system. As depicted in FIG. 35 ,vibrational energy transmitted into the driveshaft damper is convertedinto heat energy (e.g., due to the flexing of the damper materials). Asdepicted in FIG. 36 , vibrations within the driveshaft damper arecontinuously reflected until converted into heat energy.

As noted, other damping materials may be used in addition to or in lieuof foam. For example, the exemplary driveshaft damper having asingle-start “triple-ridge” attenuation strip with surficial foam asdepicted in FIGS. 29-33 could be constructed using alternatives to foam,such as corrugated paper or paperboard, polymeric batting, or textileshaving thicknesses between about 1/16 inch and 2 inches. For example, anexemplary textile acoustic insulation (e.g., sound-absorbing textile)includes a nonwoven having rayon and polyester (e.g., polyethyleneterephthalate), such as a 7-millimeter (0.275-inch) thick nonwovenhaving a basis weight of about 805 g/m². The polyester can be selectedto function either as a low-temperature binder (e.g., having a melttemperature of about 110° C.) or, for heat-treatment applications suchas swaging, a high-temperature binder (e.g., having a melt temperatureof about 180° C.).

Other damping materials include fiberglass mats, carbon-fiber mats, andtextile nonwovens (including rayon and polyester). Exemplary textilenonwovens may be needle-punched and thermally bonded. Damping materialsalso include felts, including polyester felts and wool felts (e.g.,needle-punched felts or pressed felts). Exemplary felts might have basisweights between about 0.5 lb/yd² and 10 lbs/yd² (e.g., between about 1.3g/m² and 26 g/m²). Damping materials also include recycled yarns, knitfabrics, woven fabrics, and other high-loft textiles (e.g., cotton orshoddy). Exemplary nonwovens might have basis weights between about 0.5oz/ft² and 100 oz/ft² (e.g., between about 1.3 g/m² and 260 g/m²). Anyof these damping materials can include binders to provide improvedthermal properties in order to limit thermal degradation (e.g., loss ofresilience or rebound).

As noted, the present disclosure embraces helically-wound driveshaftdampers and convolute driveshaft dampers, whereby the core may be formedfrom multiple plies of core material (smooth and/or single-facecorrugated paper) wound or wrapped around a mandrel in a helical orconvolute manner. For example, FIG. 37 is an isolated view of a helicalcore 1622 formed from smooth paper. As another example, the solid linesin FIG. 38 depict a convolute core 1722 formed from single-facecorrugated paperboard. The dashed lines in FIG. 38 schematically depictthat the convolute core 1722 may be formed by wrapping the sheet ofpaperboard from which the convolute core 1722 may be formed. The coresmay include any suitable joints. As schematic examples, FIG. 39 depictsa helical core 1822 with a seam gap joint 1868, FIG. 40 depicts ahelical core 1922 with a butt joint 1970, and FIG. 41 depicts a helicalcore 2022 with an overlap joint 2072.

The foregoing embodiments of the driveshaft damper can optionallyinclude one or more wrapping layers securely positioned atop theexterior attenuation strips and/or any exterior second damping material(e.g., foam or textile acoustic insulation). For example, theattenuation strips and any exterior second damping material areeffectively sandwiched between the outer surface of the substantiallycylindrical core and the wrapping layer(s). Such wrapping layer(s) maybe spirally wound plies or convolute plies of fibrous material (e.g.,paper or paperboard). Spirally wound plies may be configured to formseam gap joints, butt joints, and/or overlap joints. For example, FIGS.42 and 43 depict a version of the driveshaft damper 20 that includessuch an outer wrapping layer 80 and an optional strip of surficial foam62. The wrapping layer(s) may include one or more moisture-resistantlayers (e.g., parchment paper, or polymeric film or sheet). In anembodiment that excludes any exterior second damping material, theattenuation strip(s) are sandwiched between the outer surface of thesubstantially cylindrical core and the wrapping layer(s).

In some exemplary embodiments, a driveshaft damper may include indicia(e.g., exterior surface indicia) to facilitate product identification.Exemplary surface-indica can be positioned (e.g., printed or laseretched) on the interior surface and/or the exterior surface of thedriveshaft damper, and perhaps on the edge of the substrate core (e.g.,the outer edge of a paperboard tube). In this regard, the term “indicia”is intended to broadly embrace any machine-readable indicia, includingbarcodes, QR codes, matrix codes, 1D codes, 2D codes, RFID tags, IRtags, near-field-communication (NFC) tags, laser markings and codes(e.g., etchings or engravings), and other readable characters or symbols(e.g., readable via optical character recognition (OCR)). Indicia aretypically graphical representations of information or data (e.g.,associated product information), such as product numbers or trackingnumbers, that are machine-readable via an indicia-reading device (e.g.,a scanner). As noted, the surface indicia are typically printed or laseretched onto the driveshaft damper but alternatively can be applied by alabel or a sticker.

Indicia-reading devices (e.g., barcode scanners) are often employedduring manufacturing (e.g., along a production line) to verify thatcorrect parts are being used at the point of installation orconsumption. For example, in a driveshaft-manufacturing area, usingdriveshaft dampers with surface indicia would help to ensure that acorrect driveshaft damper is being installed into the correspondingpropshaft tube. This kind of verification ensures the driveshaft tubewill achieve the desired NVH when installed in a vehicle, provided thedriveshaft damper is properly designed for corresponding driveshafttube.

Manufacturing driveshafts presents practical problems, however, becausedifferent (but similarly sized) driveshaft dampers can be correctly (orincorrectly) installed into a particular driveshaft tube, or the samekind of driveshaft damper can be correctly (or incorrectly) installedinto different (but similarly sized) driveshaft tubes. By way ofillustration, a driveshaft manufacturer might opt to install afoam-wrapped driveshaft damper with a 5.0-inch outer diameter into analuminum propshaft tube having a 4.75-inch inner diameter (e.g.,5.0-inch outer diameter with a 0.125-inch aluminum wall) to yield adesired 0.25-inch interference fit. If the same driveshaft manufactureris also producing for other driveshafts an aluminum propshaft tubehaving a 4.8-inch inner diameter (e.g., 5.0-inch outer diameter with a0.100-inch aluminum wall), the manufacturer might opt to install asimilar (but slightly larger) foam-wrapped driveshaft damper with a5.05-inch outer diameter to achieve the desired 0.25-inch interferencefit. In these kind of manufacturing conditions in which different kindsof driveshaft dampers and propshaft tubes are available, the opportunityfor human error is heightened. For example, a first driveshaft damperintended for a first propshaft might be incorrectly installed in asecond propshaft, and a second driveshaft damper intended for a secondpropshaft might be incorrectly installed in a first propshaft. Thesekinds of logistical problems are exacerbated where there are manydifferent kinds of propshaft tubes and many distinct kinds of driveshaftdampers.

Similar to FIG. 29 , FIGS. 73-74 depict an exemplary driveshaft damper20 having a single-start “triple-ridge” attenuation strip with foammounted to the outer surface of the core. Both FIG. 29 and FIG. 73depict a driveshaft damper 20 (e.g., FIGS. 1, 9, 26, and 27 ) thatfurther includes a helically configured strip of foam 62 (e.g.,surficial foam, such as polyether foam) mounted (e.g., via adhesivematerial) to the outer surface of the core 22 (e.g., FIGS. 9, 26 , and27). In contrast to the driveshaft-damper embodiment depicted in FIG. 29, the exemplary driveshaft-damper embodiment depicted in FIGS. 73-74includes a helical gap G (e.g., a 0.25-1.0 inch gap measuredlongitudinally along the driveshaft damper, such as a 0.5-inchseparation) between one edge of the attenuation strip 24 and one edge ofthe strip of foam 62. Here, the gap G exposes an outer ply of the core22 (e.g., the outermost strip of paper forming a paperboard core).

As depicted in FIGS. 73-74 , surface indicia 39 are provided (e.g.,printed, laser etched, or otherwise applied) on the exterior surface ofcore 22 (e.g., printed on the outermost strip of paper forming apaperboard core). Typically, the indicia are provided on an outer stripof paper (e.g., the outermost strip of paper) before (e.g., pre-printedcodes on a reel) or during the manufacture of the paperboard core 22.For example, the indicia may be applied to the outermost strip of paper(e.g., a paper web) forming the helically-wound paperboard core 22 by anin-line printer or an in-line laser as the core material is fed to andwound around a mandrel. Marking the driveshaft damper 20 duringmanufacturing (e.g., in-line application of the surface indicia) willreduce the opportunities for mismarking with incorrect indicia. In thisregard, FIGS. 10-12 depict exemplary winding machines that are suitablefor making an exemplary helically-wound driveshaft damper.Alternatively, the indicia might be applied to or otherwise provided onthe driveshaft damper 20 after the paperboard core 22 is formed, such asusing an in-situ, laser-marking technique.

Typically, the machine-readable indicia 39 are positioned on theexterior of the driveshaft damper 20, such as an outer layer of the core22, as this simplifies scanning of the machine-readable indicia. In somecases, it is possible to include the machine-readable indicia on aninner ply (e.g., a second ply from the top) if the indicia shows throughor is otherwise readable through the more outer plies (e.g., theoutermost ply). For example, a scanner might be able to read orotherwise detect obscured (e.g., covered) indicia through one or moreplies of paper.

In an exemplary embodiment of manufacturing a driveshaft damper,machine-readable indicia are applied to a strip of paper (e.g., viaprinting and/or laser etching), and then plies of core material,including the strip of paper having machine-readable indicia, arehelically wound around a mandrel to form a core, such as depicted inFIGS. 10-12 . Concurrently, one or more attenuation strips are helicallywound around and secured to the core as the core advances longitudinallyalong the mandrel. Typically, the machine-readable indicia are at leastpartly positioned on the core's exterior surface in a helical gap formedby the one or more helically-wound attenuation strips.

In a related embodiment, damping material(s) (e.g., foam strips orbeads, polymeric batting, or polymeric nonwovens), which are typically adifferent composition from the one or more helically-wound attenuationstrips, are mounted to the core in a portion of the helical gap formedby the one or more helically-wound attenuation strips. Typically, aportion of the machine-readable indicia on the core's exterior surfaceremains visible within the remaining portion of the helical gap formedby the one or more helically-wound attenuation strips and not obscuredby the mounted damping material, such as depicted in FIGS. 73-74 .

In another embodiment, surface-indicia are provided on the attenuationstrip 24 (e.g., the flatter portion of the “triple-ridge” attenuationstrip depicted in FIGS. 73-74 ). While it may be possible to providesurface-indicia on the foam strip, the foam's porous nature makes it apoorer choice for indicia-printing or indicia-reading than either theoutermost paper ply or an attenuation strip, if present.

In yet another embodiment, such where foam substantially covers theoutermost surface of the paperboard tube as depicted in commonlyassigned U.S. Pat. No. 8,801,526, surface-indicia are provided on theinner surface of the core, typically toward one or both ends of the coreto facilitate reading of the indicia by an indicia-reading device (e.g.,a hand-held scanner). For example, surface-indicia may be provided onthe interior surface of the core by printing or laser etching on aninner strip of paper (e.g., the innermost strip of paper) forming apaperboard core before (e.g., pre-printed codes on a reel) or, moretypically, during the manufacture of the paperboard core. Even so,scanning indicia positioned on the interior surface of a core can beawkward and sometimes difficult unless the indicia are well positionedfor access by the indicia-reading device (e.g., the driveshaft dampercan turn, which can likewise rotate the indicia away from a mounted orhand-held scanner).

Working Examples (Driveshaft Dampers)

In the following Tables 2-7, the designation “SAS” refers to adriveshaft damper having a single-start attenuation strip and thedesignation “DAS” refers to a driveshaft damper having dual-startattenuation strips. The “EP” designation refers to the number ofelongate protrusions on each attenuation strip.

Table 2 (below) provides exemplary technical specifications forprototype driveshaft dampers. For the sake of comparison, theseexemplary driveshaft dampers are configured for a 30-inch aluminumdriveshaft (e.g., a representative propshaft) having an outer diameterof 4.5 inches, a wall thickness of 0.83 inch, and an inner diameter of4.334 inches (i.e., outer diameter less double the wall thickness).

TABLE 2 SAS-1EP DAS-1EP SAS-3EP DAS-3EP SAS-3EP (4.625″) (4.625″)(4.625″) (4.625″) (6.0″) driveshaft outer diameter (inch) 4.5 4.5 4.54.5 4.5 wall thickness (inch) 0.083 0.083 0.083 0.083 0.083 innerdiameter (inch) 4.334 4.334 4.334 4.334 4.334 damper outer diameter(inch) 4.484 4.484 4.484 4.484 4.484 length (inch) 13.75 13.75 13.7513.75 13.75 interference fit (inch) 0.15 0.15 0.15 0.15 0.15 paper-tubecore outer diameter D (inch) 4.03 4.03 4.03 4.03 4.03 paper width w(inch) 4.625 4.625 4.625 4.625 6.0 winding angle θ_(w) (º) 68.6 68.668.6 68.6 61.7 paper pitch length L_(w) (inch) 4.97 4.97 4.97 4.97 6.81attenuation strips rubber composition silicone silicone siliconesilicone silicone protrusions per strip 1 1 3 3 3 number of strips 1 2 12 1 strip base width (inch) 0.82 0.82 2.20 2.20 2.20 BPR 3.3 3.3 8.8 8.88.8 PSR — — 3.2 3.2 3.2 pitch length L (inch) 4.97 4.97 4.97 4.97 6.81effective pitch L_(e) (inch) 4.97 2.49 1.66 0.83 2.27 effective pitchratio (P_(e)) 0.81 1.62 2.43 4.87 1.77 pitch angle θ (º) 68.6 68.6 68.668.6 61.7 effective pitch angle θ_(e) (°) 68.6 78.9 82.5 86.3 79.8

Table 3 (below) provides exemplary technical specifications forprototype driveshaft dampers 20 depicted in FIGS. 1, 26, and 27(single-start “triple-ridge” attenuation strip), prototype driveshaftdampers 320 depicted in FIGS. 5 and 28 (dual-start “triple-ridge”attenuation strips), and the prototype driveshaft dampers depicted FIGS.29-31 (single-start “triple-ridge” attenuation strip with 0.25-inchsurficial polyether foam). U.S. Patent Application No. 62/748,204 forDriveshaft Dampers and Systems and Methods for Making and Using the Same(filed Oct. 19, 2018), which is incorporated by reference in itsentirety, includes as Appendix I photographs of the respective prototypedriveshaft dampers illustrated in FIGS. 1, 5 , and 26-31. For the sakeof comparison, these exemplary driveshaft dampers are configured for a30-inch aluminum driveshaft having an outer diameter of 4.5 inches, awall thickness of 0.83 inch, and an inner diameter of 4.334 inches(i.e., outer diameter less double the wall thickness). Table 3 comparesthe technical specifications for prototype “thick-walled” driveshaftdampers formed using 4.625-inch paper and prototype “thin-walled”driveshaft dampers formed using 4.75-inch paper.

TABLE 3 SAS-3EP SAS-3EP DAS-3EP DAS-3EP (4.625″) (4.75″) (4.625″)(4.75″) driveshaft outer diameter (inch) 4.5 4.5 4.5 4.5 wall thickness(inch) 0.083 0.083 0.083 0.083 inner diameter (inch) 4.334 4.334 4.3344.334 damper outer diameter (inch) 4.484 4.484 4.484 4.484 length (inch)13.75 13.75 13.75 13.75 interference fit (inch) 0.15 0.15 0.15 0.15paper-tube core outer diameter D (inch) 4.03 4.03 4.03 4.03 innerdiameter (inch) 3.61 3.83 3.61 3.83 wall thickness (inch) 0.21 0.10 0.210.1 paper width w (inch) 4.625 4.75 4.625 4.75 winding angle θ_(w) (º)68.6 68.0 68.6 68.0 paper pitch length L_(w) (inch) 4.97 5.12 4.97 5.12attenuation strips rubber composition EPDM or silicone EPDM or siliconeEPDM or silicone EPDM or silicone protrusions per strip 3 3 3 3 numberof strips 1 1 2 2 strip base width (inch) 2.20 2.20 2.20 2.20 BPR 8.88.8 8.8 8.8 PSR 3.2 3.2 3.2 3.2 pitch length L (inch) 4.97 5.12 4.975.12 effective pitch L_(e) (inch) 1.66 1.71 0.83 0.85 effective pitchratio (P_(e)) 2.43 2.36 4.87 4.72 pitch angle θ (º) 68.6 68.0 68.6 68.0effective pitch angle θ_(e) (°) 82.6 82.3 86.3 86.1

Table 4 (below) provides prophetic technical specifications forprototype driveshaft dampers. For the sake of comparison, theseexemplary driveshaft dampers are configured for a driveshaft having anouter diameter of 4.5 inches, a wall thickness of 0.83 inch, and aninner diameter of 4.334 inches (i.e., outer diameter less double thewall thickness). The first two comparative examples (below), namely“SAS-1EP (0.828″)” and “DAS-1EP (1.65″),” cannot be manufactured onconventional helical-winding machines because the winding angle is tooextreme using paper strips that are too narrow for the target diameterof the paper-tube core. The other exemplary driveshaft dampers vary thenumber and width of the attenuation strips (e.g., 2.2-inch attenuationstrip and 4.4-inch attenuation strip).

TABLE 4 SAS-1EP DAS-1EP SAS-6EP SAS-6EP* DAS-6EP (0.828″) (1.65″)(4.625″) (4.625″) (4.625″) damper outer diameter (inch) 4.484 4.4844.484 4.484 4.484 length (inch) 13.75 13.75 13.75 13.75 13.75interference fit (inch) 0.15 0.15 0.15 0.15 0.15 paper-tube core outerdiameter D (inch) 4.03 4.03 4.03 4.03 4.03 paper width w (inch) 0.8281.65 4.625 4.625 4.625 winding angle θ_(w) (º) 86.3 82.5 68.6 68.6 68.6paper pitch length L_(w) (inch) 0.83 1.66 4.97 4.97 4.97 attenuationstrips protrusions per strip 1 1 6 6 6 number of strips 1 2 1 1 2 stripbase width (inch) 0.82 0.82 2.2 4.4 2.2 BPR 3.3 3.3 8.8 17.6 8.8 PSR — —1.3 3.0 1.3 pitch length L (inch) 0.83 1.66 4.97 4.97 4.97 effectivepitch L_(e) (inch) 0.83 0.83 0.83 0.83 0.41 effective pitch ratio(P_(e)) 4.86 4.84 4.87 4.87 9.73 pitch angle θ (º) 86.3 82.5 68.6 68.668.6 effective pitch angle θ_(e) (°) 86.3 86.2 86.3 86.3 88.1

Table 5 (below) provides additional prophetic technical specificationsfor prototype driveshaft dampers. For the sake of comparison, theseexemplary driveshaft dampers are configured for a driveshaft having anouter diameter of 4.5 inches, a wall thickness of 0.83 inch, and aninner diameter of 4.334 inches (i.e., outer diameter less double thewall thickness).

TABLE 5 SAS-4EP DAS-4EP SAS-5EP DAS-5EP SAS-16EP (4.625″) (4.625″)(4.625″) (4.625″) (4.625″) damper outer diameter (inch) 4.484 4.4844.484 4.484 4.484 length (inch) 13.75 13.75 13.75 13.75 13.75interference fit (inch) 0.15 0.15 0.15 0.15 0.15 paper-tube core outerdiameter D (inch) 4.03 4.03 4.03 4.03 4.03 paper width w (inch) 4.6254.625 4.625 4.625 4.625 winding angle θ_(w) (º) 68.6 68.6 68.6 68.6 68.6paper pitch length L_(w) (inch) 4.97 4.97 4.97 4.97 4.97 attenuationstrips protrusions per strip 4 4 5 5 16 number of strips 1 2 1 2 1 stripbase width (inch) 2.2 2.2 2.2 2.2 4.0 BPR 8.8 8.8 8.8 8.8 16 PSR 2.1 2.11.6 1.6 0.91 pitch length L (inch) 4.97 4.97 4.97 4.97 4.97 effectivepitch L_(e) (inch) 1.24 0.62 0.99 0.50 0.31 effective pitch ratio(P_(e)) 3.24 6.49 4.06 8.11 13.0 pitch angle θ (º) 68.6 68.6 68.6 68.668.6 effective pitch angle θ_(e) (°) 84.4 87.2 85.5 87.8 88.6

Table 6 (below) provides exemplary technical specifications forprototype driveshaft dampers having “double-ridge” attenuation strips(i.e., “single-start” or “dual-start” embodiments). The “double-ridge”attenuation strips measured about 1 5/16-inch wide with the elongateprotrusions spaced 0.8 inch from one another. The prototype driveshaftdampers include light-wall paperboard cores constructed using 4.625-inchpaper strips, 6-inch paper strips, or 4-inch paper strips (“DAS-2EP—4.0”is a prophetic example.) These exemplary driveshaft dampers areconfigured for a 30-inch aluminum driveshaft (e.g., a representativepropshaft) having an outer diameter of 4.5 inches, a wall thickness of0.83 inch, and an inner diameter of 4.334 inches (i.e., outer diameterless double the wall thickness).

TABLE 6 SAS-2EP DAS-2EP SAS-2EP DAS-2EP SAS-2EP DAS-2EP (4.625″)(4.625″) (6.0″) (6.0″) (4.0″) (4.0″) driveshaft outer diameter (inch)4.5 4.5 4.5 4.5 4.5 4.5 wall thickness (inch) 0.083 0.083 0.083 0.0830.083 0.083 inner diameter (inch) 4.334 4.334 4.334 4.334 4.334 4.334damper outer diameter (inch) 4.484 4.484 4.484 4.484 4.484 4.484 length(inch) 13.75 13.75 13.75 13.75 13.75 13.75 interference fit (inch) 0.150.15 0.15 0.15 0.15 0.15 damper weight (lb) 0.594 0.746 0.556 0.6700.614 0.786 paper-tube core outer diameter D (inch) 4.03 4.03 4.03 4.034.03 4.03 paper width w (inch) 4.625 4.625 6.0 6.0 4.0 4.0 winding angleθ_(w) (°) 68.6 68.6 61.7 61.7 71.6 71.6 paper pitch length L_(w) (inch)4.97 4.97 6.81 6.81 4.22 4.22 core weight (lb) 0.442 0.442 0.442 0.4420.442 0.442 attenuation strips rubber composition EPDM EPDM EPDM EPDMEPDM EPDM protrusions per strip 2 2 2 2 2 2 number of strips 1 2 1 2 1 2strip base width (inch) 1.31 1.31 1.31 1.31 1.31 1.31 strip weight (lb)0.152 0.304 0.114 0.228 0.172 0.344 BPR 5.25 5.25 5.25 5.25 5.25 5.25PSR 3.2 3.2 3.2 3.2 3.2 3.2 pitch length L (inch) 4.97 4.97 6.81 6.814.22 4.22 effective pitch L_(e) (inch) 2.49 1.24 3.41 1.70 2.11 1.06effective pitch ratio (P_(e)) 1.62 3.24 1.18 2.37 1.91 3.82 pitch angleθ (°) 68.6 68.6 61.7 61.7 71.6 71.6 effective pitch angle θ_(e) (°) 78.984.4 74.9 82.3 80.6 85.2

Table 7 (below) provides exemplary technical specifications forprototype driveshaft dampers formed using 4 5/16-inch paper as the outerply. For the sake of comparison, these exemplary driveshaft dampers areconfigured for a 30-inch steel driveshaft (e.g., a representativepropshaft) having an outer diameter of 3.15 inches, a wall thickness of0.062 inch, and an inner diameter of 3.026 inches (i.e., outer diameterless double the wall thickness).

TABLE 7 SAS-3EP DAS-3EP (4.3125″) (4.3125″) driveshaft outer diameter(inch) 3.15 3.15 wall thickness (inch) 0.062 0.062 inner diameter (inch)3.026 3.026 damper outer diameter (inch) 3.175 3.175 length (inch) 9.759.75 interference fit (inch) 0.15 0.15 paper-tube core outer diameter D(inch) 2.701 2.701 paper width w (inch) 4.3125 4.3125 winding angleθ_(w) (º) 59.5 59.5 paper pitch length L_(w) (inch) 5.01 5.01attenuation strips rubber composition silicone EPDM protrusions perstrip 3 3 number of strips 1 2 strip base width (inch) 2.20 2.20 BPR 8.88.8 PSR 3.2 3.2 pitch length L (inch) 5.01 5.01 effective pitch L_(e)(inch) 1.67 0.83 effective pitch ratio (P_(e)) 1.62 3.24 pitch angle θ(º) 59.5 59.5 effective pitch angle θ_(e) (°) 78.9 84.4

Bench Testing

Bench testing measured frequency response function (FRF) for exemplarydampened driveshafts. For each of the following bench tests, frequencyresponse function (FRF) was measured at the midpoint of the freelypositioned aluminum propshaft (FIGS. 44-61 ) or steel propshaft (FIGS.62-66 ). For example, a damper is positioned approximately in the centerof the aluminum propshaft tube to provide a tube-damper test assembly.The tube-damper test assembly is suspended in a free-free state (i.e.,no external forces are damping the assembly). FRF testing is performedusing a data acquisition system (i.e., sound-analysis equipmentincluding a hammer and an accelerometer). The accelerometer islongitudinally positioned at the midpoint of the propshaft tube, and theexcitation point (i.e., the testing device's strike point) isapproximately 180 degrees from the accelerometer at the samelongitudinal midpoint.

In accordance with the present disclosure, the length and interferencefit of the driveshaft damper may be chosen to modify the dampingcharacteristics of the driveshaft damper (e.g., to reduce or shiftresonance frequencies) as installed in a particular propshaft.Similarly, the composition or durometer of the elastomeric material thatforms an attenuation strip or the wall thickness and outside diameter ofthe paper-tube core may be chosen to modify the damping characteristicsof the driveshaft damper (e.g., to reduce or shift resonancefrequencies) as installed in a particular propshaft.

FIG. 44 —Empty Aluminum Propshaft Tube

As a baseline, frequency response was established for an empty, 30-inchaluminum propshaft tube having an outer diameter of 4.5 inches, a wallthickness of 0.083 inch, and an inner diameter of 4.334 inches (i.e.,outer diameter less double the wall thickness). This representativepropshaft, which is described in the working examples of Tables 2-6(above), is the aluminum propshaft used in each of the following benchtests for frequency response function (FRF). FIG. 44 demonstrates theempty aluminum tube has natural resonance frequencies at 434 Hz (36.6dB), 592 Hz (43.5 dB), and 1096 Hz (29.4 dB). NVH frequencies betweenabout 390 and 410 Hz (e.g., about 400 Hz) and particularly between about600 Hz and 625 Hz are especially problematic in the automotive industry.

FIG. 45 —Comparative Driveshaft Damper

FIG. 45 depicts the frequency response function (FRF) for the 30-inchaluminum propshaft tube dampened with a centrally positioned, 14-inchpaperboard driveshaft damper having one EPDM rubber attenuation stripwith a single protrusion (i.e., SAS-1EP). The driveshaft damper's outerdiameter of 4.424 inches provides an interference fit of 0.09 inch. FIG.45 demonstrates the dampened driveshaft has peak resonance frequenciesat 414 Hz (25.7 dB), 566 Hz (20.1 dB), and 1060 Hz (10.8 dB). FIG. 45shows this kind of driveshaft damper effectively dampens NVH.

FIG. 46 —Dual-Start “Triple-Ridge” Driveshaft Damper

FIG. 46 depicts the frequency response function (FRF) for the 30-inchaluminum propshaft tube dampened with a centrally positioned, 13.75-inchpaperboard driveshaft damper having two EPDM rubber attenuation stripswith three spaced protrusions (i.e., DAS-3EP). The driveshaft damper'souter diameter of 4.54 inches provides an interference fit of 0.206inch. FIG. 46 demonstrates the dampened driveshaft has peak resonancefrequencies at 460 Hz (11.6 dB) and 581 Hz (19.0 dB). FIG. 46 shows thiskind of exemplary driveshaft damper effectively dampens NVH, reducingthe NVH levels from the comparative driveshaft damper depicted FIG. 45 .

FIG. 47 —Dual-Start “Triple-Ridge” Driveshaft Damper

FIG. 47 depicts the frequency response function (FRF) for the 30-inchaluminum propshaft tube dampened with a centrally positioned, 8.25-inchpaperboard driveshaft damper having two EPDM rubber attenuation stripswith three spaced protrusions (i.e., DAS-3EP). As compared with thesimilar “heavy-wall” driveshaft damper depicted FIG. 46 , this“light-wall” paper core has a thickness of about 0.10 inch (i.e., 0.10inch vs. 0.225 inch). The driveshaft damper's outer diameter of 4.54inches provides an interference fit of 0.206 inch. FIG. 47 demonstratesthe dampened driveshaft has peak resonance frequencies at 403 Hz (14.5dB) and 975 Hz (1.9 dB). FIG. 47 shows this kind of exemplary driveshaftdamper effectively dampens NVH and is especially effective ateliminating NVH around 600 dB—and indeed through the frequency rangebetween about 430 Hz and 900 Hz.

FIG. 48 —Comparative “SAS-1EP” Driveshaft Damper

FIG. 48 depicts the frequency response function (FRF) for the 30-inchaluminum propshaft tube dampened with a centrally positioned, 13.75-inchpaperboard driveshaft damper having one 50-durometer silicone rubberattenuation strip with a single protrusion (i.e., SAS-1EP). Thetechnical specifications for this “SAS-1EP” driveshaft damper arepresented in Table 2 (above). FIG. 48 demonstrates the dampeneddriveshaft has peak resonance frequencies at 446 Hz (2.0 dB), 603 Hz(21.0 dB), and 1071 Hz (5.8 dB). FIG. 48 shows this kind of driveshaftdamper effectively dampens NVH.

FIG. 49 —Comparative “DAS-1EP” Driveshaft Damper

FIG. 49 depicts the frequency response function (FRF) for the 30-inchaluminum propshaft tube dampened with a centrally positioned, 13.75-inchpaperboard driveshaft damper having two 50-durometer silicone rubberattenuation strips with a single protrusion (i.e., DAS-1EP). Thetechnical specifications for this “DAS-1EP” driveshaft damper arepresented in Table 2 (above). FIG. 49 demonstrates the dampeneddriveshaft has peak resonance frequencies at 400 Hz (6.8 dB), 623 Hz(10.4 dB), 986 Hz (3.7 dB), and 1073 Hz (5.4 dB). FIG. 49 shows thiskind of driveshaft damper effectively dampens NVH.

FIG. 50 —“SAS-3EP” Driveshaft Damper

FIG. 50 depicts the frequency response function (FRF) for the 30-inchaluminum propshaft tube dampened with a centrally positioned, 13.75-inchpaperboard driveshaft damper having one 50-durometer silicone rubberattenuation strip with three protrusions spaced 0.8-inch apart (i.e.,SAS-3EP). The technical specifications for this “SAS-3EP” driveshaftdamper are presented in Table 2 (above). FIG. 50 demonstrates thedampened driveshaft has peak resonance frequencies at 398 Hz (16.2 dB),541 Hz (1.2 dB), 765 Hz (3.1 dB), and 991 Hz (3.3 dB). FIG. 50 showsthis kind of single-start “triple-ridge” driveshaft damper effectivelydampens NVH and is especially effective at eliminating NVH around 600 dB(i.e., shifting the resonance frequency from the problematic-automotivefrequency of 600 Hz to 625 Hz)—and indeed nearly eliminating NVH throughthe frequency range between about 425 Hz and 725 Hz.

FIG. 51 —“DAS-3EP” Driveshaft Damper

FIG. 51 depicts the frequency response function (FRF) for the 30-inchaluminum propshaft tube dampened with a centrally positioned, 13.75-inchpaperboard driveshaft damper having two 50-durometer silicone rubberattenuation strips with three protrusions spaced 0.8-inch apart (i.e.,DAS-3EP). The technical specifications for this “DAS-3EP” driveshaftdamper are presented in Table 2 (above). FIG. 51 demonstrates thedampened driveshaft has peak resonance frequencies at 383 Hz (16.5 dB)and 543 Hz (12.4 dB). FIG. 51 shows this kind of driveshaft dampereffectively dampens NVH. FIG. 51 shows this kind of dual-start“triple-ridge” driveshaft damper effectively dampens NVH and isespecially effective at eliminating NVH around 600 dB (i.e., shiftingthe resonance frequency from the problematic-automotive frequency of 600Hz to 625 Hz)—and indeed eliminating NVH through the frequency rangebetween about 575 Hz and 1100 Hz.

FIG. 52 —Surficial-Foam “SAS-3EP” Driveshaft Damper

FIG. 52 depicts the frequency response function (FRF) for the 30-inchaluminum propshaft tube dampened with a centrally positioned, 13.75-inchpaperboard driveshaft damper having one 50-durometer EPDM rubberattenuation strip with three protrusions spaced 0.8-inch apart (i.e.,SAS-3EP) and 0.25-inch surficial polyether foam with a density of 1.5lbs/ft³. This composite damper design is illustrated in FIGS. 29-31(single-start silicone “triple-ridge” attenuation strip with 0.25-inchsurficial polyether foam). Technical specifications for this“thin-walled” composite driveshaft damper—except for the surficialfoam—are presented in Table 3 (above) as “SAS-3EP (4.75″).” FIG. 52demonstrates the dampened driveshaft has peak resonance frequencies at398 Hz (11.2 dB), 549 Hz (0.0 dB), and 1050 Hz (4.1 dB). FIG. 52 showsthis kind of single-start “triple-ridge” driveshaft damper withsurficial foam effectively dampens NVH, is especially effective ateliminating NVH around 600 dB (i.e., shifting the resonance frequencyfrom the problematic-automotive frequency of 600 Hz to 625 Hz), andkeeps resonance noise under 0 dB from about 415 Hz and 918 Hz.

FIG. 53 —Surficial-Foam “SAS-3EP” Driveshaft Damper

FIG. 53 depicts the frequency response function (FRF) for the 30-inchaluminum propshaft tube dampened with a centrally positioned, 10.5-inchpaperboard driveshaft damper having one 50-durometer EPDM rubberattenuation strip with three protrusions spaced 0.8-inch apart (i.e.,SAS-3EP) and 0.25-inch surficial polyether foam. This composite damperdesign is illustrated in FIGS. 29-31 (single-start EPDM “triple-ridge”attenuation strip with 0.25-inch surficial polyether foam). Technicalspecifications for this “thin-walled” composite driveshaft damper—exceptfor the 10.5-inch damper length and the surficial foam—are presented inTable 3 (above) as “SAS-3EP (4.75″).” FIG. 53 demonstrates the dampeneddriveshaft has peak resonance frequencies 409 Hz (12.6 dB), 556 Hz (1.1dB), and 1017 Hz (3.4 dB). FIG. 53 shows this kind of single-start“triple-ridge” driveshaft damper with surficial foam effectively dampensNVH and is especially effective at eliminating NVH around 600 dB (i.e.,shifting the resonance frequency from the problematic-automotivefrequency of 600 Hz to 625 Hz).

FIG. 54 —“SAS-2EP” Driveshaft Damper (4.625-Inch Paper)

FIG. 54 depicts the frequency response function (FRF) for the 30-inchaluminum propshaft tube dampened with a centrally positioned, 13.75-inchpaperboard driveshaft damper having one 50-durometer EPDM rubberattenuation strip with two protrusions spaced 0.8-inch apart (i.e.,SAS-2EP). The light-wall paperboard core is constructed using a4.625-inch top-ply paper strip. The driveshaft damper's outer diameterof 4.484 inches provides an interference fit of 0.150 inch. Thetechnical specifications for this “SAS-2EP” driveshaft damper arepresented in Table 6 (above). FIG. 54 demonstrates the dampeneddriveshaft has peak resonance frequencies at 402 Hz (11.9 dB), 706 Hz(1.0 dB), and 1091 Hz (6.5 dB). FIG. 54 shows this kind of single-start“double-ridge” driveshaft damper effectively dampens NVH and isespecially effective at eliminating NVH around 600 dB (i.e., shiftingthe resonance frequency from the problematic-automotive frequency of 600Hz to 625 Hz).

FIG. 55 —“DAS-2EP” Driveshaft Damper (4.625-Inch Paper)

FIG. 55 depicts the frequency response function (FRF) for the 30-inchaluminum propshaft tube dampened with a centrally positioned, 13.75-inchpaperboard driveshaft damper having two 50-durometer EPDM rubberattenuation strips each with two protrusions spaced 0.8-inch apart(i.e., DAS-2EP). The light-wall paperboard core is constructed using a4.625-inch top-ply paper strip. The driveshaft damper's outer diameterof 4.484 inches provides an interference fit of 0.150 inch. Thetechnical specifications for this “DAS-2EP” driveshaft damper arepresented in Table 6 (above). FIG. 55 demonstrates the dampeneddriveshaft has peak resonance frequencies at 403 Hz (19.6 dB), 553 Hz(18.1 dB), and 997 Hz (5.62 dB). FIG. 55 shows this kind of dual-start“double-ridge” driveshaft damper effectively dampens NVH whileperforming differently than the single-start “double-ridge” driveshaftdamper of FIG. 54 .

FIG. 56 —“SAS-2EP” Driveshaft Damper (6.0-inch paper)

FIG. 56 depicts the frequency response function (FRF) for the 30-inchaluminum propshaft tube dampened with a centrally positioned, 13.75-inchpaperboard driveshaft damper having one 50-durometer EPDM rubberattenuation strip with two protrusions spaced 0.8-inch apart (i.e.,SAS-2EP). The light-wall paperboard core is constructed using a 6.0-inchtop-ply paper strip. The driveshaft damper's outer diameter of 4.484inches provides an interference fit of 0.150 inch. The technicalspecifications for this “SAS-2EP” driveshaft damper are presented inTable 6 (above). FIG. 56 demonstrates the dampened driveshaft has peakresonance frequencies at 405 Hz (10.2 dB), 626 Hz (7.0 dB), and 1011 Hz(8.0 dB). FIG. 56 shows this kind of single-start “double-ridge”driveshaft damper effectively dampens NVH.

FIG. 57 —“DAS-2EP” Driveshaft Damper (6.0-inch paper)

FIG. 57 depicts the frequency response function (FRF) for the 30-inchaluminum propshaft tube dampened with a centrally positioned, 13.75-inchpaperboard driveshaft damper having two 50-durometer EPDM rubberattenuation strips each with two protrusions spaced 0.8-inch apart(i.e., SAS-2EP). The light-wall paperboard core is constructed using a6.0-inch top-ply paper strip. The driveshaft damper's outer diameter of4.484 inches provides an interference fit of 0.150 inch. The technicalspecifications for this “DAS-2EP” driveshaft damper are presented inTable 6 (above). FIG. 57 demonstrates the dampened driveshaft has peakresonance frequencies at 399 Hz (14.5 dB), 544 (2.7 dB), 933 Hz (2.0dB), and 1117 Hz (7.3 dB). FIG. 57 shows this kind of dual-start“double-ridge” driveshaft damper effectively dampens NVH and isespecially effective at eliminating NVH around 600 dB (i.e., shiftingthe resonance frequency from the problematic-automotive frequency of 600Hz to 625 Hz) while performing differently than the single-start“double-ridge” driveshaft dampers of FIG. 54 and FIG. 56 .

FIG. 58 —“SAS-2EP” Driveshaft Damper (4.0-inch paper)

FIG. 58 depicts the frequency response function (FRF) for the 30-inchaluminum propshaft tube dampened with a centrally positioned, 13.75-inchpaperboard driveshaft damper having one 50-durometer EPDM rubberattenuation strip with two protrusions spaced 0.8-inch apart (i.e.,SAS-2EP). The light-wall paperboard core is constructed using a 4.0-inchtop-ply paper strip. The driveshaft damper's outer diameter of 4.484inches provides an interference fit of 0.150 inch. The technicalspecifications for this “SAS-2EP” driveshaft damper are presented inTable 6 (above). FIG. 58 demonstrates the dampened driveshaft has peakresonance frequencies at 403 Hz (14.0 dB), 721 (1.4 dB), and 1033 Hz(7.6 dB). FIG. 58 shows this kind of single-start “double-ridge”driveshaft damper effectively dampens NVH and is especially effective ateliminating NVH around 600 dB (i.e., shifting the resonance frequencyfrom the problematic-automotive frequency of 600 Hz to 625 Hz).

FIG. 59 —Dual Driveshaft Dampers

FIG. 59 depicts the frequency response function (FRF) for the 30-inchaluminum propshaft tube dampened with both (i) a 9.75-inch paperboarddriveshaft damper having one 50-durometer silicone rubber attenuationstrip with three protrusions spaced 0.8-inch apart (i.e., SAS-3EP) and(ii) a 13.75-inch paperboard driveshaft damper having one 50-durometersilicone rubber attenuation strip with a single protrusion (i.e.,SAS-1EP). The technical specifications for the “SAS-3EP” driveshaftdamper—except for the 9.75-inch damper length—are presented in Table 2(above) as “SAS-3EP (4.625″).” The technical specifications for this“SAS-1EP” driveshaft damper are presented in Table 2 (above) as “SAS-1EP(4.625″).” FIG. 59 shows this combination of two different kinds ofdriveshaft dampers effectively dampens NVH at both theproblematic-automotive frequencies of 400 Hz and 600 Hz.

FIG. 60 —Dual Driveshaft Dampers

FIG. 60 depicts the frequency response function (FRF) for the 30-inchaluminum propshaft tube dampened with both (i) a 13.75-inch paperboarddriveshaft damper having one 50-durometer silicone rubber attenuationstrip with three protrusions spaced 0.8-inch apart (i.e., SAS-3EP) and(ii) a 13.75-inch paperboard driveshaft damper having one 50-durometersilicone rubber attenuation strip with a single protrusion (i.e.,SAS-1EP). The technical specifications for the “SAS-3EP” driveshaftdamper are presented in Table 2 (above) as “SAS-3EP (6.0″).” Thetechnical specifications for the “SAS-1EP” driveshaft damper arepresented in Table 2 (above) as “SAS-1EP (4.625″).” FIG. 60 demonstratesthe dampened driveshaft has peak resonance frequencies at 388 Hz (6.1dB), 637 Hz (6.3 dB), and 1056 Hz (8.2 dB). FIG. 60 shows thiscombination of two different kinds of driveshaft dampers effectivelydampens NVH at both the problematic-automotive frequencies of 400 Hz and600 Hz.

FIG. 61 —Comparative Foam-Slug Driveshaft Damper

FIG. 61 depicts the frequency response function (FRF) for the 30-inchaluminum propshaft tube dampened with a centrally positioned, 20-inchfoam slug. FIG. 61 shows this kind of driveshaft damper dampens NVH,albeit less effectively at the problematic-automotive frequencies of 400Hz and 600 Hz than the foregoing driveshaft dampers according to thepresent disclosure.

FIG. 62 —Empty Steel Propshaft Tube

As a baseline, frequency response was established for an empty, 30-inchsteel propshaft tube having an outer diameter of 3.15 inches, a wallthickness of 0.062 inch, and an inner diameter of 3.026 inches (i.e.,outer diameter less double the wall thickness). This representativepropshaft, which is described in the working examples of Table 7(above), is the steel propshaft used in each of the following benchtests for frequency response function (FRF). FIG. 62 demonstrates theempty steel tube has natural resonance frequencies at 656 Hz (37.8 dB),722 Hz (41.8 dB), and 815 Hz (34.2 dB). Problematic NVH frequencies thataffect steel are different from the problematic frequencies that affectaluminum, and this is illustrated by the differences in baseline testingbetween FIG. 44 (empty aluminum tube) and FIG. 62 (empty steel tube).

FIG. 63 —Comparative Driveshaft Damper

FIG. 63 depicts the frequency response function (FRF) for the 30-inchsteel propshaft tube dampened with a centrally positioned, 10.625-inchpaperboard driveshaft damper having an outermost layer of single-facecorrugated paper. The driveshaft damper's outer diameter of 3.086 inchesprovided an interference fit of 0.06 inch. FIG. 63 demonstrates thedampened driveshaft has peak resonance frequencies at 646 Hz (13.0 dB),658 Hz (28.3 dB), 718 Hz (33.3 dB), and 802 Hz (30.7 dB). FIG. 63 showsthis kind of driveshaft damper effectively dampens NVH.

FIG. 64 —Single-Start “Triple-Ridge” Driveshaft Damper

FIG. 64 depicts the frequency response function (FRF) for the 30-inchsteel propshaft tube dampened with a centrally positioned, 9.75-inchpaperboard driveshaft damper having one 50-durometer silicone rubberattenuation strip with three protrusions spaced 0.8-inch apart (i.e.,SAS-3EP). The technical specifications for this “SAS-3EP” driveshaftdamper are presented in Table 7 (above). The driveshaft damper's outerdiameter of 3.175 inches provides an interference fit of 0.150 inch.FIG. 64 demonstrates the dampened driveshaft has peak resonancefrequencies at 651 Hz (21.5 dB) and 713 Hz (19.9 dB). FIG. 64 shows thiskind of exemplary driveshaft damper effectively dampens NVH, reducingthe NVH levels from the comparative driveshaft damper depicted FIG. 63 .

FIG. 65 —Dual-Start “Triple-Ridge” Driveshaft Damper

FIG. 65 depicts the frequency response function (FRF) for the 30-inchsteel propshaft tube dampened with a centrally positioned, 15.75-inchpaperboard driveshaft damper having two 50-durometer EPDM rubberattenuation strips with three protrusions spaced 0.8-inch apart (i.e.,DAS-3EP). The technical specifications for this “DAS-3EP” driveshaftdamper are presented in Table 7 (above). The driveshaft damper's outerdiameter of 3.175 inches provides an interference fit of 0.150 inch.FIG. 65 demonstrates the dampened driveshaft has peak resonancefrequencies at 641 Hz (13.8 dB), 656 Hz (16.7 dB), and 707 Hz (20.86dB). FIG. 65 shows this kind of exemplary driveshaft damper effectivelydampens NVH, reducing the NVH levels from the comparative driveshaftdamper depicted FIG. 63 .

FIG. 66 —Dual Driveshaft Dampers

FIG. 66 depicts the frequency response function (FRF) for the 30-inchsteel propshaft tube dampened with both (i) 10.625-inch paperboarddriveshaft damper having an outermost layer of single-face corrugatedpaper as described with respect to FIG. 63 and (ii) 9.75-inch paperboarddriveshaft damper having one 50-durometer silicone rubber attenuationstrip with three protrusions spaced 0.8-inch apart (i.e., SAS-3EP). Thetechnical specifications for the “SAS-3EP” driveshaft damper arepresented in Table 7 (above) as “SAS-3EP (4.3125″).” FIG. 66demonstrates the dampened driveshaft has peak resonance frequencies at647 Hz (17.5 dB), 713 Hz (19.8 dB), and 812 Hz (7.6 dB). FIG. 66 showsthis combination of two different kinds of driveshaft damperseffectively dampens NVH.

Working Examples (Spring-Mass Systems)

Tables 8-13 (below) illustrate various tuned mass dampers (i.e., activemass dampers or harmonic absorbers) via the modification of the inherentspring-mass system. Tables 8-13 describe the selective adjustment (e.g.,addition) of mass to exemplary driveshaft dampers by changing theprofile of the EPDM “double-ridge” attenuation strip (i.e., thestandard, heavy, and heavier embodiments). Tables 8-13 also illustrateadjusting mass (e.g., increasing mass or decreasing mass) by changingthe winding angle of the paperboard tube's helical winding and thus thepitch angle of each attenuation strip. As noted, winding angle θ_(w)generally depends on the width of the plies of core material and thediameter of the core, and the pitch angle θ of each attenuation stripmatches the winding angle θ_(w) of the plies of core material.

In Tables 8-13 (below), the designation “SAS” refers to a driveshaftdamper having a single-start attenuation strip and the designation “DAS”refers to a driveshaft damper having dual-start attenuation strips. The“EP” designation refers to the number of elongate protrusions on eachattenuation strip (e.g., “2EP” refers to two elongate protrusions oneach attenuation strip).

Tables 8-13 illustrate the prophetic application of three exemplary“double-ridge” attenuation strips having different thicknesses and mass.Each of these prophetic driveshaft dampers is configured for an aluminumpropshaft tube having an outer diameter of 4.50 inches, a wall thicknessof 0.083 inch, and an inner diameter of 4.334 inches (i.e., outerdiameter less double the wall thickness) such as described in theworking examples of Tables 2-6 (above) and FRF-characterized in FIG. 44.

The three exemplary embodiments of “double-ridge” attenuation strips areformed from extruded 50-durometer ethylene propylene diene monomer(EPDM) rubber. Each attenuation strip has a maximum height of 0.250 inchand a nominal width of 1.640 inches. For each “double-ridge” attenuationstrip, the two elongate protrusions are spaced 0.800 inch apart measuredcenter-to-center. That said, the three exemplary embodiments of“double-ridge” attenuation strips—standard, heavy, and heavier—havedifferent thicknesses (e.g., attenuation-strip base thickness) asrespectively described (above) with reference to FIGS. 16A, 16B, 16C asthe first version of the double-ridge attenuation strip 824, the secondversion of the double-ridge attenuation strip 824, and the third versionof the double-ridge attenuation strip 824, respectively.

The “standard” attenuation-strip embodiment has a thickness of 0.054inch between the two elongate protrusions and a thickness of 0.030 inchat the outer end of each adhesion flange. This “standard” EPDMattenuation strip has a mass per length of 0.0516 lb/ft. This exemplary“double-ridge” attenuation strip is depicted in FIG. 16A.

The “heavy” attenuation-strip embodiment is one millimeter (0.039 inch)thicker than the “standard” “double-ridge” attenuation-strip embodimentwith a thickness of 0.093 inch between the two elongate protrusions anda thickness of 0.069 inch at the outer end of each adhesion flange. This“heavy” EPDM attenuation strip has a mass per length of 0.0792 lb/ft.This exemplary “double-ridge” attenuation strip is depicted in FIG. 16B.

The “heavier” attenuation-strip embodiment is two millimeters (0.079inch) thicker than the “standard” “double-ridge” attenuation-stripembodiment with a thickness of 0.132 inch between the two elongateprotrusions and a thickness of 0.108 inch at the outer end of eachadhesion flange. This “heavier” EPDM attenuation strip has a mass perlength of 0.108 lb/ft. This exemplary “double-ridge” attenuation stripis depicted in FIG. 16C.

“Double-Ridge” Attenuation Strips on a “Light Wall” Core

Tables 8-10 (below) illustrate the prophetic application of the threeexemplary “double-ridge” attenuation strips to three different,light-wall paperboard cores constructed using (i) 4.625-inch paperstrips (Table 8), (ii) 6-inch paper strips (Table 9), and (iii) 4-inchpaper strips (Table 10). Each resulting paperboard core has an innerdiameter of 3.830 inches, an outer diameter of 4.030 inches, a wallthickness of 0.100 inch, and a length of 13.75 inches.

Table 8 (below) illustrates the prophetic application of the threeexemplary EPDM “double-ridge” attenuation strips (i.e., the standard,heavy, and heavier embodiments) in both single-start and dual-startconfigurations to a light-wall paperboard core formed using a 4.625 inchtop-ply paper strip. The winding angle θ_(w) of the outer ply and thematching pitch angle θ of each attenuation strip is 68.6 degrees. Thepitch length of each attenuation strip is 4.97 inches. Each“single-start” driveshaft damper requires 3.131 feet of attenuationstrip, and each “dual-start” driveshaft damper requires 6.262 feet ofattenuation strip.

TABLE 8 3.83″ ID × 4.03″ OD × 0.100″ wall × 13.75″ L; winding angleθ_(w) = 68.6º; pitch length L = 4.97 core mass (lb) strip mass (lb)damper mass (lb) “light wall” SAS-2EP “standard” attenuation strip0.3825 0.1616 0.5441 “heavy” attenuation strip (+1 mm) 0.3825 0.24800.6305 “heavier” attenuation strip (+2 mm) 0.3825 0.3381 0.7206 “lightwall” DAS-2EP “standard” attenuation strip 0.3825 0.3232 0.7057 “heavy”attenuation strip (+1 mm) 0.3825 0.4960 0.8785 “heavier” attenuationstrip (+2 mm) 0.3825 0.6762 1.0587

Table 9 (below) illustrates the prophetic application of the threeexemplary EPDM “double-ridge” attenuation strips (i.e., the standard,heavy, and heavier embodiments) in both single-start and dual-startconfigurations to a light-wall paperboard core formed using a 6-inchtop-ply paper strip. The winding angle θ_(w) of the outer ply and thematching pitch angle θ of each attenuation strip is 61.7 degrees. Thepitch length of each attenuation strip is 6.81 inches. Each“single-start” driveshaft damper requires 2.414 feet of attenuationstrip, and each “dual-start” driveshaft damper requires 4.828 feet ofattenuation strip. As compared with Table 8, Table 9 demonstrates usingwider strips of paper to form the paperboard core reduces the windingangle of the paperboard tube's helical winding and the pitch angle ofeach attenuation strip. This increases the pitch length of eachattenuation strip and lessens the total mass of the driveshaft damper.

TABLE 9 3.83″ ID × 4.03″ OD × 0.100″ wall × 13.75″ length; winding angleθ_(w) = 61.7º; pitch length L = 6.81 core mass (lb) strip mass (lb)damper mass (lb) “light wall” SAS-2EP “standard” attenuation strip0.3825 0.1246 0.5071 “heavy” attenuation strip (+1 mm) 0.3825 0.19120.5737 “heavier” attenuation strip (+2 mm) 0.3825 0.2607 0.6432 “lightwall” DAS-2EP “standard” attenuation strip 0.3825 0.2492 0.6317 “heavy”attenuation strip (+1 mm) 0.3825 0.3824 0.7649 “heavier” attenuationstrip (+2 mm) 0.3825 0.5214 0.9039

Table 10 (below) illustrates the prophetic application of the threeexemplary EPDM “double-ridge” attenuation strips (i.e., the standard,heavy, and heavier embodiments) in both single-start and dual-startconfigurations to a light-wall paperboard core formed using a 4-inchtop-ply paper strip. The winding angle θ_(w) of the outer ply and thematching pitch angle θ of each attenuation strip is 71.6 degrees. Thepitch length of each attenuation strip is 4.22 inches. Each“single-start” driveshaft damper requires 3.620 feet of attenuationstrip, and each “dual-start” driveshaft damper requires 7.240 feet ofattenuation strip. As compared with Table 8, Table 10 demonstrates usingnarrower strips of paper to form the paperboard core increases thewinding angle of the paperboard tube's helical winding and the pitchangle of each attenuation strip. This decreases the pitch length of eachattenuation strip and increases the total mass of the driveshaft damper.

TABLE 10 3.83″ ID × 4.03″ OD × 0.210″ wall × 13.75″ length; windingangle θ_(w) = 71.6º; pitch length L = 4.22 core mass (lb) strip mass(lb) damper mass (lb) “light wall” SAS-2EP “standard” attenuation strip0.3825 0.1868 0.5693 “heavy” attenuation strip (+1 mm) 0.3825 0.28670.6692 “heavier” attenuation strip (+2 mm) 0.3825 0.3910 0.7735 “lightwall” DAS-2EP “standard” attenuation strip 0.3825 0.3736 0.7561 “heavy”attenuation strip (+1 mm) 0.3825 0.5734 0.9559 “heavier” attenuationstrip (+2 mm) 0.3825 0.7820 1.1645“Double-Ridge” Attenuation Strips on a “Heavy Wall” Core

Tables 11-13 (below) illustrate the prophetic application of the threeexemplary “double-ridge” attenuation strips to three different,heavy-wall paperboard cores constructed using (i) 4.625-inch paperstrips (Table 11), (ii) 6-inch paper strips (Table 12), and (iii) 4-inchpaper strips (Table 13). Each resulting paperboard core has an innerdiameter of 3.610 inches, an outer diameter of 4.030 inches, a wallthickness of 0.210 inch, and a length of 13.75 inches.

Table 11 (below) illustrates the prophetic application of the threeexemplary EPDM “double-ridge” attenuation strips (i.e., the standard,heavy, and heavier embodiments) in both single-start and dual-startconfigurations to a heavy-wall paperboard core formed using a 4.625-inchtop-ply paper strip. The winding angle θ_(w) of the outer ply and thematching pitch angle θ of each attenuation strip is 68.6 degrees. Thepitch length of each attenuation strip is 4.97 inches. Each“single-start” driveshaft damper requires 3.135 feet of attenuationstrip, and each “dual-start” driveshaft damper requires 6.27 feet ofattenuation strip.

TABLE 11 3.61″ ID × 4.03″ OD × 0.210″ wall × 13.75″ length; windingangle θ_(w) = 68.6º; pitch length L = 4.97 core mass (lb) strip mass(lb) damper mass (lb) “heavy wall” SAS-2EP “standard” attenuation strip0.7817 0.1618 0.9435 “heavy” attenuation strip (+1 mm) 0.7817 0.24831.0300 “heavier” attenuation strip (+2 mm) 0.7817 0.3386 1.1203 “heavywall” DAS-2EP “standard” attenuation strip 0.7817 0.3236 1.1053 “heavy”attenuation strip (+1 mm) 0.7817 0.4966 1.2783 “heavier” attenuationstrip (+2 mm) 0.7817 0.6772 1.4589

Table 12 (below) illustrates the prophetic application of the threeexemplary EPDM “double-ridge” attenuation strips (i.e., the standard,heavy, and heavier embodiments) in both single-start and dual-startconfigurations to a heavy-wall paperboard core formed using a 6-inchtop-ply paper strip. The winding angle θ_(w) of the outer ply and thematching pitch angle θ of each attenuation strip is 61.7 degrees. Thepitch length of each attenuation strip is 6.81 inches. Each“single-start” driveshaft damper requires 2.417 feet of attenuationstrip, and each “dual-start” driveshaft damper requires 4.834 feet ofattenuation strip. As compared with the Table 11, Table 12 demonstratesusing wider strips of paper to form the paperboard core reduces thewinding angle of the paperboard tube's helical winding and the pitchangle of each attenuation strip. This increases the pitch length of eachattenuation strip and lessens the total mass of the driveshaft damper.

TABLE 12 3.61″ ID × 4.03″ OD × 0.210″ wall × 13.75″ length; windingangle θ_(w) = 61.7º; pitch length L = 6.81 core mass (lb) strip mass(lb) damper mass (lb) “heavy wall” SAS-2EP “standard” attenuation strip0.7817 0.1247 0.9064 “heavy” attenuation strip (+1 mm) 0.7817 0.19140.9731 “heavier” attenuation strip (+2 mm) 0.7817 0.2610 1.0427 “heavywall” DAS-2EP “standard” attenuation strip 0.7817 0.2494 1.0311 “heavy”attenuation strip (+1 mm) 0.7817 0.3828 1.1645 “heavier” attenuationstrip (+2 mm) 0.7817 0.5220 1.3037

Table 13 (below) illustrates the prophetic application of the threeexemplary EPDM “double-ridge” attenuation strips (i.e., the standard,heavy, and heavier embodiments) in both single-start and dual-startconfigurations to a heavy-wall paperboard core formed using a 4-inchtop-ply paper strip. The winding angle θ_(w) of the outer ply and thematching pitch angle θ of each attenuation strip is 71.6 degrees. Thepitch length of each attenuation strip is 4.22 inches. Each“single-start” driveshaft damper requires 3.625 feet of attenuationstrip, and each “dual-start” driveshaft damper requires 7.250 feet ofattenuation strip. As compared with the Table 11, Table 13 demonstratesusing narrower strips of paper to form the paperboard core increases thewinding angle of the paperboard tube's helical winding and the pitchangle of each attenuation strip. This decreases the pitch length of eachattenuation strip and increases the total mass of the driveshaft damper.

TABLE 13 3.61″ ID × 4.03″ OD × 0.210″ wall × 13.75″ length; windingangle θ_(w) = 71.6º; pitch length L = 4.22 core mass (lb) strip mass(lb) damper mass (lb) “heavy wall” SAS-2EP “standard” attenuation strip0.7817 0.1871 0.9688 “heavy” attenuation strip (+1 mm) 0.7817 0.28711.0688 “heavier” attenuation strip (+2 mm) 0.7817 0.3915 1.1732 “heavywall” DAS-2EP “standard” attenuation strip 0.7817 0.3742 1.1559 “heavy”attenuation strip (+1 mm) 0.7817 0.5742 1.3559 “heavier” attenuationstrip (+2 mm) 0.7817 0.7830 1.5647

Driveshaft-Damper Tuning

One or more driveshaft dampers may be installed in a driveshaft todampen or attenuate noise, vibration, and harshness (NVH), and eachdriveshaft damper may be configured to function as a dynamic absorber ortuned mass damper. A driveshaft damper can be “tuned” to provideimproved NVH reduction by reducing problematic NVH for a particulardriveshaft as installed in a particular vehicle (e.g., to achievebroad-band tuning). For example, the concept of drive-shaft dampertuning is illustrated in the frequency-response-function bench testingas depicted in FIGS. 44-61 (aluminum propshaft) and FIGS. 62-66 (steelpropshaft) and as presented in corresponding Tables 8-13.

As noted, an attenuation strip's mass, density, thickness, resilience,durometer (hardness), length, and material of construction, as well asthe attenuation strip's number of protrusions and correspondingprotrusion height, can be selected and adjusted to dampen a particularlyproblematic resonance frequency. In this way, attenuation strips may beconfigured so that the driveshaft damper oscillates with a desired phaseshift with respect to a resonance frequency of one or more NVHcomponents. Similarly, the mass, density, wall thickness, length, andmaterial of construction of the substantially cylindrical structure(e.g., a tubular structure, such as a paperboard core or tube) and/or asupplemental damping material's mass, density, thickness, resilience,durometer (hardness), and material of construction can be selected andadjusted to dampen a particularly problematic resonance frequency (e.g.,to help achieve a tuned driveshaft damper). Exemplary problematicfrequencies include those caused by shell-mode NVH (e.g., reverberationof the driveshaft tube), bending-mode NVH (e.g., bending of thedriveshaft tube), and/or torsion-mode NVH (e.g., longitudinal twistingof the driveshaft tube).

By way of non-limiting illustration, for a particular powertraindriveshaft, the properties of the substantially cylindrical structure(e.g., the paperboard core or tube) are first selected to provide adesired fit, especially considering the base tube's mass, length, andwall thickness. The base tube's wall thickness and length may be variedto achieve a satisfactory mass. Then, the kinds of attenuation strips(e.g., number of protrusions, protrusion height, mass, density,thickness, resilience, durometer, length, and composition) and thenumber of attenuation strips (e.g., whether to employ a single-startattenuation strip or dual-start attenuation strips) are configured(e.g., pitch angle) to shift the frequency response from NVH peaks. Inpractice, after a near-frequency solution is discovered by varying somedriveshaft-damper properties, such as ±30 Hz for a 500-Hz solution(e.g., reducing unwanted NVH frequencies between ˜470 Hz and ˜530 Hz),fine tuning (e.g., micro-adjusting the frequency) to within ±15 Hz for a500-Hz solution (e.g., ˜485 Hz to ˜515 Hz) might be achieved by furtheradjusting pitch length (or the related pitch angle) and interferencefit.

In accordance with the present disclosure, exemplary tuned driveshaftdampers can include one or more attenuation strips (e.g., a single-startor a dual-start configuration), each having one or more protrusions asherein disclosed (one, two, three, four, or five elongate protrusions,etc.), and, optionally, supplemental damping material (e.g., a seconddamping material such as foam, textile acoustic insulation, batting, orsingle-face corrugated paper). One exemplary tuned driveshaft dampermight include only a single-start attenuation strip having one elongateprotrusion, and another exemplary tuned driveshaft damper might includetwo or more attenuation strips each having one elongate protrusion(e.g., a dual-start or a tri-start configuration). Another exemplarytuned driveshaft damper might include only a single-start attenuationstrip having two or more elongate protrusions (e.g., a “triple-ridge”attenuation strip or greater). Other exemplary tuned driveshaft dampersmay include a first attenuation strip having one or more elongateprotrusions (e.g., a “single-ridge” attenuation strip, a “double-ridge”attenuation strip, or a “triple-ridge” attenuation strip, etc.), and asecond attenuation strip might include two or more elongate protrusions(e.g., a “double-ridge” attenuation strip or a “triple-ridge”attenuation strip, etc.).

As previously noted, in exemplary driveshaft-damper embodiments usingtwo or more different styles of attenuation strips, the attenuationstrips may be formed of the same kind of material having differentdurometers (e.g., a 50 Shore A durometer attenuation strip and a 70Shore A durometer attenuation strip) or different materials (e.g., EPDMrubber and heat-resistant silicone rubber) having similar or differentdurometers. As noted, exemplary elastomeric material for use in theattenuation strips may have a Shore hardness between 20 and 100 Shore Adurometer. Similarly, each of these exemplary tuned driveshaft dampersmay further include supplemental damping material as herein disclosed(e.g., high-temperature foam, high-temperature textile acousticinsulation, high-temperature batting or nonwovens, or single-facecorrugated paper that can withstand swaging operations). Without beingbound to any theory, it has been observed that varying the number andproperties of the attenuation strips facilitates frequency-responseshifts at problematic NVH frequencies.

As noted, the attenuation strips, the supplemental damping material(e.g., foam, textile acoustic insulation, batting, or single-facecorrugated paper), and the substantially cylindrical core operate as aspring-mass system, which can dampen vibration by moving the mass out ofphase with the vibration source. The one or more attenuation strips andthe supplemental damping material, if present, may represent the spring,and the substantially cylindrical core (e.g., a tubular paperboard core)may represent the mass in this spring-mass system. The properties of theattenuation strips, the supplemental damping material, and/or thesubstantially cylindrical core can be varied to dampen specificresonance frequencies so that the driveshaft damper functions as a tunedmass damper (e.g., an active mass damper or harmonic absorber). Withreference to FIGS. 34-36 , a tuned driveshaft damper provides aspring-mass system whose oscillations quickly decay (e.g., due to springrate and/or hysteresis damping) after being deflected because of contactbetween a vibrating driveshaft and the driveshaft damper. Vibrationalenergy transmitted into the driveshaft damper is continuously convertedinto heat energy (e.g., due to the flexing of the damper materials).With respect to damper tuning, the configuration and properties of theone or more attenuation strips (e.g., the compressive elasticity of theelongate protrusions) can be selected and/or adjusted to change thespring rates or force constants of the spring-mass system.

In accordance with the foregoing, an exemplary NVH-reducing driveshaftdamper includes a tubular structure (e.g., a paperboard tube) having aninner surface and an outer surface and one or more attenuation stripshelically wound around the tubular structure at a pitch angle θ andpositioned (e.g., mounted) on the tubular structure. Here, thedriveshaft damper's tubular structure and its one or morehelically-wound attenuation strips are configured to dampen at least oneproblematic resonance frequency (e.g., problematic-automotivefrequencies between 600 Hz and 625 Hz).

In one embodiment, at least one helically-wound attenuation strip has atleast two elongate protrusions having respective heights within a5-percent variation (e.g., 5 percent or less) from one another, such asdepicted in FIG. 15 . In another embodiment, at least onehelically-wound attenuation strip has at least three elongateprotrusions having respective heights within a 5-percent variation(e.g., 5 percent or less) from one another, such as depicted in FIG. 17. In a related embodiment, the NVH-reducing driveshaft damper includestwo or more helically-wound attenuation strips each having at least twoelongate protrusions, wherein at least one helically-wound attenuationstrip has at least two elongate protrusions having respective heightswithin a 5-percent variation (e.g., 3 percent or less, such as 2 percentof less) from one another.

In yet another embodiment, damping material(s) are mounted to thetubular core in a helical gap formed by the one or more attenuationstrips helically wound around the tubular structure, such as depicted inFIGS. 29 and 73-74 . Typically, such damping materials (e.g., foamstrips or beads, polymeric batting, polymeric nonwovens, or othersound-absorbing textiles) are a different structure and composition fromthe helically-wound attenuation strips.

These kinds of exemplary NVH-reducing driveshaft dampers can beinstalled within a tubular driveshaft's internal annular space (e.g.,compressively positioned and frictionally secured within the tubulardriveshaft). Typically, the driveshaft damper's tubular structure, theone or more helically-wound attenuation strips, and the optional dampingmaterial(s) are configured to dampen at least one problematic resonancefrequency in the tubular driveshaft (and/or at least one problematicresonance frequency in a vehicle in which the dampened driveshaft isinstalled). In accordance with the foregoing, where two exemplaryNVH-reducing driveshaft dampers are installed within a tubulardriveshaft's internal annular space (e.g., dual driveshaft dampers), thecombination of the first driveshaft damper and the second driveshaftdamper is configured to dampen one or more problematic resonancefrequencies in the tubular driveshaft (and/or at least one problematicresonance frequency in a vehicle in which the dampened driveshaft isinstalled).

Supplemental Bench Testing

Supplemental bench testing further illustrated tuning a driveshaftdamper to provide improved NVH reduction by reducing problematic NVH fora particular driveshaft. As an exemplary tuning exercise, thissupplemental bench testing measured frequency response function (FRF)for an exemplary driveshaft dampened using other dampers (e.g.,comparative driveshaft dampers). For each of the following bench tests,frequency response function (FRF) was measured at the midpoint of thefreely positioned aluminum propshaft (FIGS. 67-72 ). As before, a damperis positioned approximately in the center of the aluminum propshaft tubeto provide a tube-damper test assembly. The tube-damper test assembly issuspended in a free-free state (i.e., no external forces are damping theassembly). FRF testing is performed using a data acquisition system(i.e., sound-analysis equipment including a hammer and anaccelerometer). The accelerometer is longitudinally positioned at themidpoint of the propshaft tube, and the excitation point (i.e., thetesting device's strike point) is approximately 180 degrees from theaccelerometer at the same longitudinal midpoint.

FIG. 67 —Empty Aluminum Propshaft Tube

As a baseline, frequency response was established for an empty, 30-inchaluminum propshaft tube having an outer diameter of 4.0 inches, a wallthickness of 0.093 inch, and an inner diameter of 3.814 inches (i.e.,outer diameter less double the wall thickness). This representativepropshaft, which is described in the working examples of Table 14(below), is the aluminum propshaft used in each of the following benchtests for frequency response function (FRF). FIG. 67 demonstrates theempty aluminum tube has natural resonance frequencies at 635 Hz (39.3dB), 735 Hz (41.6 dB), and 983 Hz (31.6 dB). As discussed previously,NVH frequencies between about 390 and 410 Hz (e.g., about 400 Hz) andparticularly between about 600 Hz and 625 Hz are especially problematicin the automotive industry.

FIG. 68 —Comparative “SAS-1EP” Driveshaft Damper

FIG. 68 depicts the frequency response function (FRF) for the 30-inchaluminum propshaft tube dampened with a centrally positioned,14.173-inch paperboard driveshaft damper constructed using 4.3125-inchpaper (i.e., the width of the outermost strip of paper forming thehelically-wound, paper-tube core is 4 5/16 inches) and having one EPDMrubber attenuation strip (55 Shore A durometer) with a central0.200-inch “E-profile” protrusion (i.e., SAS-1EP). The driveshaftdamper's outer diameter of 3.924 inches provides an interference fit of0.110 inch within the propshaft. The technical specifications for this“SAS-1EP” driveshaft damper are presented in Table 14 (below). FIG. 68demonstrates the dampened driveshaft has peak resonance frequencies at596 Hz (21.3 dB), 711 Hz (23.4 dB), and 954 Hz (2.9 dB). FIG. 68 showsthis kind of driveshaft damper effectively dampens NVH.

FIG. 69 —Comparative “DAS-1EP” Driveshaft Damper

FIG. 69 depicts the frequency response function (FRF) for the 30-inchaluminum propshaft tube dampened with a centrally positioned, 9.873-inchpaperboard driveshaft damper constructed using narrower 3.5-inch paper(i.e., the width of the outermost strip of paper forming thehelically-wound, paper-tube core) and having two silicone rubberattenuation strips (70 Shore A durometer) each with a single 0.250-inch“T-profile” protrusion (i.e., DAS-1EP). The driveshaft damper's outerdiameter of 4.003 inches provides an interference fit of 0.190 inchwithin the propshaft (e.g., compare FIG. 68 ). The technicalspecifications for this “DAS-1EP” driveshaft damper are presented inTable 14 (below). FIG. 69 demonstrates the dampened driveshaft has peakresonance frequencies at 592 Hz (18.9 dB), 703 Hz (12.8 dB), and 946 Hz(5.1 dB). FIG. 69 shows this kind of driveshaft damper effectivelydampens NVH.

FIG. 70 —Comparative “DAS-1EP” Driveshaft Damper

FIG. 70 depicts the frequency response function (FRF) for the 30-inchaluminum propshaft tube dampened with a centrally positioned,14.173-inch paperboard driveshaft damper constructed using 4.3125-inchpaper (i.e., the width of the outermost strip of paper forming thehelically-wound, paper-tube core) and having two EPDM rubber attenuationstrips (55 Shore A durometer) each with a central 0.200-inch “E-profile”protrusion (i.e., DAS-1EP). The driveshaft damper's outer diameter of3.924 inches provides an interference fit of 0.110 inch within thepropshaft. Here, the mass of the paper-tube core increased by increasingthe wall thickness to 0.345 inch, thereby reducing the paper-tube core'sinner diameter to 2.875 inch (e.g., compare FIGS. 68-69 ). The technicalspecifications for this “DAS-1EP” driveshaft damper are presented inTable 14 (below). FIG. 70 demonstrates the dampened driveshaft has apeak resonance frequency at 931 Hz (13.6 dB). FIG. 70 shows this kind ofdriveshaft damper effectively dampens NVH, effectively eliminating NVHfrom 0-865 Hz.

FIG. 71 —Comparative “DAS-1EP” Driveshaft Damper

FIG. 71 depicts the frequency response function (FRF) for the 30-inchaluminum propshaft tube dampened with a centrally positioned,14.173-inch paperboard driveshaft damper constructed using wider5.5-inch paper (i.e., the width of the outermost strip of paper formingthe helically-wound, paper-tube core) and having two EPDM rubberattenuation strips (55 Shore A durometer) each with a central 0.200-inch“E-profile” protrusion (i.e., DAS-1EP). The driveshaft damper's outerdiameter of 3.924 inches provides an interference fit of 0.110 inchwithin the propshaft. Here, too, the mass of the paper-tube coreincreased by increasing the wall thickness to 0.345 inch, therebyreducing the paper-tube core's inner diameter to 2.875 inch (e.g.,compare FIGS. 68-69 ). The wider 5.5-inch paper strips yield less massgain than using 4.3125-inch paper strips (e.g., compare FIG. 70 ). Thetechnical specifications for this “DAS-1EP” driveshaft damper arepresented in Table 14 (below). FIG. 71 demonstrates the dampeneddriveshaft has a peak resonance frequency at 921 Hz (13.5 dB), which isa slight shift from the peak resonance frequency (i.e., 931 Hz) shown inFIG. 70 , and reduces NVH at 931 Hz to 12.1 dB. FIG. 71 shows this kindof driveshaft damper effectively dampens NVH, effectively eliminatingNVH from 0-847 Hz.

FIG. 72 —Comparative “DAS-1EP” Driveshaft Damper

FIG. 72 depicts the frequency response function (FRF) for the 30-inchaluminum propshaft tube dampened with a centrally positioned,14.173-inch paperboard driveshaft damper constructed using 4.3125-inchpaper (i.e., the width of the outermost strip of paper forming thehelically-wound, paper-tube core) and having two EPDM rubber attenuationstrips (55 Shore A durometer) each with a central 0.200-inch “E-profile”protrusion (i.e., DAS-1EP). The driveshaft damper's outer diameter of3.924 inches provides an interference fit of 0.110 inch within thepropshaft. The mass of the paper-tube core further increased byincreasing the wall thickness to 0.455 inch, thereby further reducingthe paper-tube core's inner diameter to 2.654 inch (e.g., compare FIGS.70-71 ). The technical specifications for this “DAS-1EP” driveshaftdamper are presented in Table 14 (below). FIG. 72 demonstrates thedampened driveshaft has a peak resonance frequency at 974 Hz (9.7 dB),which is a shift from the peak resonance frequency (i.e., 931 Hz) shownin FIG. 70 , and reduces NVH at 931 Hz to 5.9 dB. FIG. 72 shows thiskind of driveshaft damper effectively dampens NVH, effectivelyeliminating NVH from 0-877 Hz.

TABLE 14 SAS-1EP DAS-1EP DAS-1EP DAS-1EP DAS-1EP (Fig. 68) (Fig. 69)(Fig. 70) (Fig. 71) (Fig. 72) (4.3125″) (3.5″) (4.3125″) (5.5″)(4.3125″) driveshaft outer diameter (inch) 4.0 4.0 4.0 4.0 4.0 wallthickness (inch) 0.093 0.093 0.093 0.093 0.093 inner diameter (inch)3.814 3.814 3.814 3.814 3.814 damper outer diameter (inch) 3.924 4.0033.924 3.924 3.924 length (inch) 14.173 9.873 14.173 14.173 14.173interference fit (inch) 0.11 0.19 0.11 0.11 0.11 paper-tube core outerdiameter D (inch) 3.564 3.545 3.564 3.564 3.564 inner diameter (inch)3.424 3.365 2.875 2.875 2.654 wall thickness (inch) 0.070 0.090 0.3450.345 0.455 mass (lbs) 0.330 0.295 1.442 1.410 1.752 paper width w(inch) 4.3125 3.5 4.3125 5.5 4.3125 winding angle θ_(w) (º) 67.3 71.867.3 60.6 67.3 paper pitch length L_(w) (inch) 4.67 3.68 4.67 6.31 4.67frequency response F1 596 Hz 592 Hz 931 Hz 921 Hz 974 Hz (21.3 dB) (18.9dB) (13.6 dB) (13.5 dB (9.7 dB) F2 711 Hz 703 Hz (23.4 dB) (12.8 dB) F3954 Hz 946 Hz (2.9 dB) (5.1 dB) attenuation strips protrusions per strip1 1 1 1 1 number of strips 1 2 2 2 2 strip base width (inch) 0.82 0.820.82 0.82 0.82 rubber composition/style EPDM silicone EPDM EPDM EPDM 55Shore A 70 Shore A 55 Shore A 55 Shore A 55 Shore A (“E” 0.200″) (“T”0.250″) (“E” 0.200″) (“E” 0.200″) (“E” 0.200″) BPR 4.1 3.3 4.1 4.1 4.1pitch length L (inch) 4.67 3.68 4.67 6.31 4.67 effective pitch L_(e)(inch) 4.67 1.84 2.34 3.16 2.34 effective pitch ratio (P_(e)) 0.76 1.931.53 1.13 1.53 pitch angle θ (°) 67.3 71.8 67.3 60.6 67.3 effectivepitch angle θ_(e) (°) 67.3 80.7 78.2 74.3 78.2

Table 14 (above) and FIGS. 67-72 demonstrate different damper designsyield different dampening characteristics for a particular propshaft,such as by varying mass, wall thickness, interference fit, andcomposition and style of the attenuation strips. As noted, a driveshaftdamper can be broadly “tuned” to provide improved NVH reduction byreducing problematic NVH for a particular driveshaft as installed in aparticular vehicle. After a near-frequency solution is identified (e.g.,+/−50 Hz or so, such as +/−30 Hz), fine tuning can be achieved byadjusting frequency response (e.g., +/−15 Hz or so, such as +/−10 Hz),such as by varying the driveshaft-damper characteristics hereindisclosed (e.g., mass, length, and materials of construction amongothers).

In accordance with the foregoing and by way of further illustration,tuning a driveshaft damper can include positioning a first driveshaftdamper within the internal annular space of a representative tubulardriveshaft. An exemplary first driveshaft damper includes (i) a firsttubular structure defining a wall, an inner surface, and an outersurface (e.g., first a helically-wound paperboard tube) and (ii) one ormore first attenuation strips helically wound around the first tubularstructure at a pitch angle θ₁ and positioned on (e.g., mounted upon orotherwise secured to) the first tubular structure. The frequencyresponse function can be measured or otherwise determined for thetubular driveshaft as dampened by the first driveshaft damper, such asillustrated in the frequency-response-function bench testing as depictedin FIGS. 44-61 (aluminum propshaft), FIGS. 62-66 (steel propshaft), andFIGS. 67-72 (aluminum propshaft), and as presented in correspondingTables 8-14. From its corresponding frequency-response-function one ormore problematic resonance frequencies can be identified for the tubulardriveshaft as dampened by the first driveshaft damper (e.g.,problematic-automotive frequencies around 400 Hz and 600 Hz).

A second driveshaft damper can then be made (e.g., designed andconstructed) to dampen at least one problematic resonance frequencyidentified in the frequency response function of the tubular driveshaftas dampened by the first driveshaft damper (e.g., using the technicalinformation achieved by frequency-response-function testing). Anexemplary second driveshaft damper includes (i) a second tubularstructure defining a wall, an inner surface, and an outer surface (e.g.,a second helically-wound paperboard tube) and (ii) one or more secondattenuation strips helically wound around the second tubular structureat a pitch angle θ₂ and positioned on (e.g., mounted upon or otherwisesecured to) the second tubular structure. Typically, the design of thesecond driveshaft damper is otherwise the same as the design of thefirst driveshaft damper except for one or more modifications to thesecond driveshaft damper's tubular structure and/or one or morehelically-wound attenuation strips

In an exemplary embodiment, relative to the first driveshaft damper, thestep of making (e.g., designing and building) the second driveshaftdamper includes adjusting the second tubular structure's wall thicknessand inside diameter to thereby change the second tubular structure'smass and/or stiffness.

In another exemplary embodiment, relative to the first driveshaftdamper, the step of making the second driveshaft damper includesadjusting the durometer of at least one of the second driveshaftdamper's one or more helically-wound attenuation strips to therebychange the second tubular structure's mass and/or stiffness.

In yet another exemplary embodiment, relative to the first driveshaftdamper, the step of making the second driveshaft damper includesadjusting the base-to-protrusion ratio BPR of at least one of the seconddriveshaft damper's one or more helically-wound attenuation strips tothereby change the second tubular structure's mass and/or stiffness.

In yet another exemplary embodiment, the first driveshaft damper's firsttubular structure and second driveshaft damper's second tubularstructure are helically-wound paperboard cores formed of a plurality ofplies of helically-wound paper strips. Here, relative to the firstdriveshaft damper, the step of making the second driveshaft damperincludes adjusting the second helically-wound paperboard core'spaper-strip width and winding angle θ_(w) to thereby change the secondtubular structure's mass and/or stiffness.

In summary and as explained previously, an attenuation strip'scharacteristics, such as mass, density, thickness, resilience, durometer(hardness), length, and material of construction, along with theattenuation strip's width, number of protrusions, and correspondingprotrusion height, can be selected and modified to dampen one or moreparticularly problematic resonance frequencies (e.g., typicalproblematic-automotive frequencies). Similarly, the tubular structure'scharacteristics, such as mass, density, wall thickness, length, andmaterial of construction and/or a supplemental damping material'scharacteristics, such as mass, density, thickness, resilience, durometer(hardness), and material of construction, can be selected and modifiedto dampen a particularly problematic resonance frequency (e.g., toachieve a tuned driveshaft damper).

Other Aspects and Embodiments

The foregoing detailed description and accompanying figures set forthtypical embodiments of driveshaft dampers for use in driveshafts todampen or attenuate noise, vibration, and harshness (NVH). The discloseddriveshaft dampers include helically-wound driveshaft dampers with oneor more attenuation strips. Also disclosed are systems and methods formaking and using such helically-wound driveshaft dampers (e.g.,combining two or more different kinds of driveshaft dampers to dampenNVH). The present disclosure is not limited to such exemplaryembodiments. It will be apparent that numerous other embodiments ofdriveshaft dampers, and systems and methods for making and usingdriveshaft dampers, may be provided in accordance with the presentdisclosure. The present disclosure may utilize any variety of aspects,features, or steps, or combinations thereof. The figures may beschematic representations that are not necessarily drawn to scale.

It is within the scope of this disclosure for one or more of the terms“substantially,” “about,” “approximately,” and/or the like, to qualifyeach adjective and adverb of the foregoing disclosure, to provide abroad disclosure. As an example, it is believed those of ordinary skillin the art will readily understand that, in different implementations ofthe features of this disclosure, reasonably different engineeringtolerances, precision, and/or accuracy may be applicable and suitablefor obtaining the desired result. Accordingly, it is believed those ofordinary skill will readily understand usage herein of the terms such as“substantially,” “about,” “approximately,” and the like.

The use of the term “and/or” includes any and all combinations of one ormore of the associated listed items. The figures are schematicrepresentations and so are not necessarily drawn to scale. Unlessotherwise noted, specific terms have been used in a generic anddescriptive sense and not for purposes of limitation.

While various aspects, features, and embodiments have been disclosedherein, other aspects, features, and embodiments will be apparent tothose having ordinary skill in the art. The various disclosed aspects,features, and embodiments are for purposes of illustration and are notintended to be limiting.

It is intended that the scope of the present invention includes at leastthe following claims and their equivalents:
 1. An NVH-reducingdriveshaft damper, comprising: a tubular structure defining an innersurface and an outer surface; and one or more attenuation stripshelically wound around the tubular structure at a pitch angle ϑ andpositioned on the tubular structure, wherein at least onehelically-wound attenuation strip has (i) at least two elongateprotrusions having respective heights within a 5-percent variation fromone another and (ii) a protrusion-spacing ratio PSR of between 3 and 5,PSR being equal to the mean spacing between adjacent elongateprotrusions divided by the protrusion height of the tallest elongateprotrusion; wherein the driveshaft damper's tubular structure and theone or more helically-wound attenuation strips are configured to dampenat least one problematic resonance frequency.
 2. The NVH-reducingdriveshaft damper according to claim 1, wherein the one or moreattenuation strips helically wound around the tubular structure comprisetwo or more helically-wound attenuation strips each having at least twoelongate protrusions, wherein each helically wound attenuation strip hasa protrusion-spacing ratio PSR of between 3 and 5, PSR being equal tothe mean spacing between adjacent elongate protrusions divided by theprotrusion height of the tallest elongate protrusion.
 3. A dampeneddriveshaft possessing NVH-reduction, comprising (i) a tubular driveshaftdefining an internal annular space and (ii) the driveshaft damperaccording to claim 1 compressively positioned and frictionally securedwithin the tubular driveshaft, wherein the driveshaft damper's tubularstructure and the one or more helically-wound attenuation strips areconfigured to dampen at least one problematic resonance frequency in thetubular driveshaft.
 4. A vehicle comprising the dampened tubulardriveshaft of claim 3, wherein the driveshaft damper's tubular structureand the one or more helically-wound attenuation strips are configured todampen at least one problematic resonance frequency in the vehicle. 5.The NVH-reducing driveshaft damper according to claim 1, comprisingdamping material mounted to the tubular structure in a helical gapformed by the one or more attenuation strips helically wound around thetubular structure, the damping material comprising a compositiondifferent from both the tubular structure and the one or morehelically-wound attenuation strips.
 6. A dampened driveshaft possessingNVH-reduction, comprising (i) a tubular driveshaft defining an internalannular space and (ii) the driveshaft damper according to claim 5compressively positioned and frictionally secured within the tubulardriveshaft, wherein the driveshaft damper's tubular structure, the oneor more helically-wound attenuation strips, and the damping material areconfigured to dampen at least one problematic resonance frequency in thetubular driveshaft.
 7. A vehicle comprising the dampened tubulardriveshaft of claim 6, wherein the driveshaft damper's tubularstructure, the one or more helically-wound attenuation strips, and thedamping material are configured to dampen at least one problematicresonance frequency in the vehicle.
 8. A dampened driveshaft possessingNVH-reduction, comprising (i) a tubular driveshaft defining an internalannular space, (ii) a first driveshaft damper according to claim 1compressively positioned and frictionally secured within the tubulardriveshaft, and (iii) a second driveshaft damper positioned within thetubular driveshaft, wherein the first driveshaft damper and the seconddriveshaft damper are differently configured and wherein the combinationof the first driveshaft damper and the second driveshaft damper isconfigured to dampen one or more problematic resonance frequencies inthe tubular driveshaft.
 9. A vehicle comprising the dampened tubulardriveshaft of claim
 8. 10. The NVH-reducing driveshaft damper accordingto claim 1, wherein, for at least one helically-wound attenuation strip,the ratio of the protrusion height of the tallest elongate protrusion tothe maximum protrusion width of the tallest elongate protrusion isbetween 2 and
 4. 11. The NVH-reducing driveshaft damper according toclaim 1, comprising machine-readable indicia positioned on the exteriorsurface of the driveshaft damper in a helical gap formed by the one ormore attenuation strips helically wound around the tubular structure.12. An NVH-reducing driveshaft damper, comprising: a tubular structuredefining an inner surface and an outer surface; and one or moreattenuation strips helically wound around the tubular structure at apitch angle ϑ and positioned on the tubular structure, wherein at leastone helically-wound attenuation strip has (i) at least three elongateprotrusions having respective heights within a 5-percent variation fromone another and (ii) a protrusion-spacing ratio PSR of between 2 and 4,PSR being equal to the mean spacing between adjacent elongateprotrusions divided by the protrusion height of the tallest elongateprotrusion; wherein the driveshaft damper's tubular structure and theone or more helically-wound attenuation strips are configured to dampenat least one problematic resonance frequency.
 13. The NVH-reducingdriveshaft damper according to claim 12, wherein the one or moreattenuation strips helically wound around the tubular structure comprisetwo or more helically-wound attenuation strips each having at least twoelongate protrusions, wherein each helically-wound attenuation strip hasa protrusion-spacing ratio PSR of between 2 and 4, PSR being equal tothe mean spacing between adjacent elongate protrusions divided by theprotrusion height of the tallest elongate protrusion.
 14. TheNVH-reducing driveshaft damper according to claim 12, wherein, for atleast one helically-wound attenuation strip, the ratio of the protrusionheight of the tallest elongate protrusion to the maximum protrusionwidth of the tallest elongate protrusion is between 2 and
 4. 15. Adampened driveshaft possessing NVH-reduction, comprising (i) a tubulardriveshaft defining an internal annular space and (ii) the driveshaftdamper according to claim 12 compressively positioned and frictionallysecured within the tubular driveshaft, wherein the driveshaft damper'stubular structure and the one or more helically-wound attenuation stripsare configured to dampen at least one problematic resonance frequency inthe tubular driveshaft.
 16. A vehicle comprising the dampened tubulardriveshaft of claim 15, wherein the driveshaft damper's tubularstructure and the one or more helically-wound attenuation strips areconfigured to dampen at least one problematic resonance frequency in thevehicle.
 17. The NVH-reducing driveshaft damper according to claim 12,comprising damping material mounted to the tubular structure in ahelical gap formed by the one or more attenuation strips helically woundaround the tubular structure, the damping material comprising acomposition different from both the tubular structure and the one ormore helically-wound attenuation strips.
 18. A dampened driveshaftpossessing NVH-reduction, comprising (i) a tubular driveshaft definingan internal annular space and (ii) the driveshaft damper according toclaim 17 compressively positioned and frictionally secured within thetubular driveshaft, wherein the driveshaft damper's tubular structure,the one or more helically-wound attenuation strips, and the dampingmaterial are configured to dampen at least one problematic resonancefrequency in the tubular driveshaft.
 19. A vehicle comprising thedampened tubular driveshaft of claim 18, wherein the driveshaft damper'stubular structure, the one or more helically-wound attenuation strips,and the damping material are configured to dampen at least oneproblematic resonance frequency in the vehicle.
 20. A dampeneddriveshaft possessing NVH-reduction, comprising (i) a tubular driveshaftdefining an internal annular space, (ii) a first driveshaft damperaccording to claim 12 compressively positioned and frictionally securedwithin the tubular driveshaft, and (iii) a second driveshaft damperpositioned within the tubular driveshaft, wherein the first driveshaftdamper and the second driveshaft damper are differently configured andwherein the combination of the first driveshaft damper and the seconddriveshaft damper is configured to dampen one or more problematicresonance frequencies in the tubular driveshaft.
 21. A vehiclecomprising the dampened tubular driveshaft of claim
 20. 22. TheNVH-reducing driveshaft damper according to claim 12, comprisingmachine-readable indicia positioned on the exterior surface of thedriveshaft damper in a helical gap formed by the one or more attenuationstrips helically wound around the tubular structure.